Method for forming an organic electroluminescence (el) element

ABSTRACT

The present invention relates to a method for forming an organic EL element having at least one pixel type comprising at least three different layers including a hole injection layer (HIL), a hole transport layer (HTL) and an emission layer (EML), characterized in that the HIL, the HTL and the EML of at least one pixel type are obtained by depositing inks wherein the layers are annealed after said depositing steps in a first, second and third annealing step and the difference of the annealing temperature of the first and of the second annealing step is below 35° C., preferably below 30° C., more preferably below 25° C. and the annealing temperature of the third annealing step is no more than 5° C. above the annealing temperature of the first and/or the second annealing step, preferably the annealing temperature of the third annealing step is equal to or below the annealing temperature of the first and the second annealing step, wherein the first annealing step is performed before the second annealing step and the second annealing step is performed before the third annealing step.

TECHNICAL FIELD

The present invention relates to a method for forming an organicelectroluminescence (EL) element.

BACKGROUND ART

Display manufacturers have great interest in organic light-emittingdiodes (OLED) for display applications. In particular, they areinterested in ink-jet printed OLED TV for its high potential for highperformance and potential low manufacture cost. The advantage of usinginkjet printing technique is the highly precise position and ink volumecontrol and its potentially high throughput for mass production. Theconventional panel contains at least red, green, and blue colors (R, G,and B). Usually, each color has multilayered device structure. The stateof art for promising display manufacture are, so-calledblue-common-layer (BCL) structure. The ink set for BCL structurecontains inks to form hole-injection layer for red (R-HIL),hole-injection layer for green (G-HIL), hole-injection layer for blue(B-HIL), hole transport layer for red (R-HTL), hole transport layer forgreen (G-HTL), hole transport layer for blue (B-HTL), green emissivelayer (G-EML), and red emissive layer (R-EML).

One of the main challenges in multi-layer printing is to identify andadjust the relevant parameters to obtain a homogeneous deposition ofinks on the substrate coupled with good device performances. Inparticular, solubility of materials, physical parameters of the solvent(surface tension, viscosity, boiling point, etc.), printing technology,processing conditions (air, nitrogen, temperature, etc.) and dryingparameters are characteristics which can drastically influence the pixelpattern and thus the device performances.

Technical Problem and Object of the Present Invention

Many inks have been proposed in organic electroluminescence (EL) devicesfor inkjet printing. However, the number of important parameters playinga role during deposition and the drying process makes the choice of theink depositing very challenging. A further challenge is that prior artinks and depositing methods may provide devices having a low efficiencyand lifetime.

Therefore, it is an object of the present invention to solve theproblems of the prior art as mentioned above. Furthermore, it is apermanent desire to improve the performance of the EL device, especiallythe layer(s) containing the organic semiconductor(s), such asefficiency, lifetime and sensitivity regarding oxidation or water.

Thus, the methods for forming an organic EL element such assemiconductors by inkjet printing still need to be improved. One objectof the present invention is to provide a method for forming an organicEL element which allows a controlled deposition to form organicsemiconductor layers having good layer properties and performance. Afurther object of the present invention is to provide a method forforming an organic EL element which allows an uniform application of inkdroplets on a substrate when used in an inkjet printing method therebygiving good layer properties and performance.

SUMMARY OF THE INVENTION

The present invention relates to a method for forming an organic ELelement having at least one pixel type comprising at least threedifferent layers including a hole injection layer (HIL), a holetransport layer (HTL) and an emission layer (EML), characterized in thatthe HIL, the HTL and the EML of at least one pixel type are obtained bydepositing inks wherein the layers are annealed after said depositingsteps in a first, second and third annealing step and the difference ofthe annealing temperature of the first and of the second annealing stepis below 35° C., preferably below 30° C., more preferably below 25° C.and the annealing temperature of the third annealing step is no morethan 5° C. above the annealing temperature of the first and/or thesecond annealing step, preferably the annealing temperature of the thirdannealing step is equal to or below the annealing temperature of thefirst and the second annealing step, wherein the first annealing step isperformed before the second annealing step and the second annealing stepis performed before the third annealing step.

The invention further relates to an organic electroluminescence (EL)device obtainable by a method as described above and below, preferablyOLED devices, in particular for rigid and flexible OLED devices.

The organic electroluminescence (EL) devices include, withoutlimitation, organic light emitting diodes (OLED), electroluminescentdisplays, organic laserdiodes (O-laser), photoconductors and organiclight emitting electrochemical cell (OLEC).

According to a preferred embodiment, the present invention providesorganic light emitting diodes (OLED). OLED devices can for example beused for illumination, for medical illumination purposes, as signalingdevices, as signage devices, and in displays. Displays can be addressedusing passive matrix driving, total matrix addressing or active matrixdriving. Transparent OLEDs can be manufactured by using opticallytransparent electrodes. Flexible OLEDs are assessable through the use offlexible substrates.

Advantageous Effects of Invention

The inventors have surprisingly found that a method for forming anorganic EL element having at least one pixel type comprising at leastthree different layers including a hole injection layer (HIL), a holetransport layer (HTL) and an emission layer (EML), characterized in thatthe HIL, the HTL and the EML of at least one pixel type are obtained bydepositing inks wherein the layers are annealed after said depositingsteps in a first, second and third annealing step and the difference ofthe annealing temperature of the first and of the second annealing stepis below 35° C., preferably below 30° C., more preferably below 25° C.and the annealing temperature of the third annealing step is no morethan 5° C. above the annealing temperature of the first and/or thesecond annealing step, preferably the annealing temperature of the thirdannealing step is equal to or below the annealing temperature of thefirst and the second annealing step, wherein the first annealing step isperformed before the second annealing step and the second annealing stepis performed before the third annealing step allows an effective inkdeposition to form uniform and well-defined organic layers of functionalmaterials which have good layer properties and very good performance.

The methods and devices of the present invention provide surprisingimprovements in the efficiency of the EL devices and the productionthereof. Unexpectedly, the performance, the lifetime and the efficiencyof the EL devices can be improved, if these devices are achieved by amethod of the present invention.

In addition thereto, the method enables a low-cost and easy printingprocess. The printing process allows a high quality printing at highspeed.

DETAILED DESCRIPTION OF THE INVENTION

The method for forming an organic EL element having at least one pixeltype comprising at least three different layers including a holeinjection layer (HIL), a hole transport layer (HTL) and an emissionlayer (EML). These layers are well known in the prior art.

As mentioned above, the present invention provides a method for formingelectroluminescence devices. These devices include elements being ableto emit light and preferably have pixels which can be controlled inorder to emit light. In the present invention, the EL elements have ahole injection layer (HIL), a hole transport layer (HTL) and an emissionlayer (EML) wherein the HIL, the HTL and the EML of at least one pixeltype are obtained by depositing inks wherein the layers are annealedafter said depositing steps in a first, second and third annealing stepand the difference of the annealing temperature of the first and of thesecond annealing step is below 35° C., preferably below 30° C., morepreferably below 25° C. and the annealing temperature of the thirdannealing step is no more than 5° C. above the annealing temperature ofthe first and/or the second annealing step, preferably the annealingtemperature of the third annealing step is equal to or below theannealing temperature of the first and the second annealing step,wherein the first annealing step is performed before the secondannealing step and the second annealing step is performed before thethird annealing step.

It should be noted that the second depositing step is done after thefirst annealing step but before the second annealing step and the thirddepositing step is done after the second annealing step.

The difference of the annealing temperature of the first and of thesecond annealing step being below 35° C., preferably below 30° C., morepreferably below 25° C. concerns the absolute value. Therefore, if theannealing temperature of the second annealing step is bigger than theannealing temperature of the first annealing step, the difference of theannealing temperature of the second and of the first annealing stepbeing below 35° C., preferably below 30° C., more preferably below 25°C.

Preferably, an organic EL element having at least two different pixeltypes including a first pixel type and a second pixel type ismanufactured and the HIL and the HTL of both pixel types and the EML ofat least one pixel type are obtained by depositing an ink and at leastone layer of both pixel types is deposited by applying an ink at thesame time, preferably an organic EL element having at least threedifferent pixel types is manufactured and the HIL and the HTL of allpixel types and the EML of at least one pixel type are obtained bydepositing an ink and at least one layer of all pixel types is depositedby applying an ink at the same time.

The expression “applying an ink at the same time” means that thedifferent inks are provided to the substrate or the layer on which theinks are applied within one step. Preferably, the ink is appliedparallel, e.g. by using ink jet technique with two or more printingheads. Especially, no drying is performed between two different inks areapplied, if the inks are applied at the same time. Preferably, the atleast two pixel types differ in their colour.

In a special embodiment, the pixel types preferably include a HIL andthe ink for obtaining a HIL comprises an organic solvent, preferably theink for obtaining a HIL comprises at least 50% by weight of one or moreorganic solvents.

Furthermore, all the pixel types may preferably include a HIL and theHIL of all pixel types is manufactured by depositing an ink, drying andannealing at the same time wherein the annealing step is performed at anannealing temperature T1.

In a preferred embodiment, the EL element preferably has three differentpixel types including a first pixel type, a second pixel type and athird pixel type and the HTL of the second pixel type and the thirdpixel type are manufactured by depositing an ink, drying and annealingat the same time wherein the annealing step is performed at an annealingtemperature T2.

In a specific embodiment of the present invention, preferably no inkconcerning the first pixel type is deposited while the HTL of the secondpixel type is manufactured.

Preferably, the HTL of the first pixel type and the EML of the secondpixel type are manufactured by depositing an ink, drying and annealingat the same time wherein the annealing step is performed at an annealingtemperature T3.

Preferably the following equations are met:

T1−T2≤35° C., preferably 30° C., more preferably 25° C.;

T2−T1≤35° C., preferably 30° C., more preferably 25° C.;

T3−T1≤5° C., preferably 0° C., more preferably −5° C.;

T3−T2≤5° C., preferably 0° C., more preferably −5° C.

In a preferred embodiment, the annealing temperature of the firstdepositing step is preferably at least 180° C., more preferably at least190° C., even more preferably at least 200° C.

In a preferred further embodiment, the annealing temperature of thesecond depositing step is preferably at least 180° C., more preferablyat least 190° C., even more preferably at least 200° C.

Furthermore, the annealing temperature of the third depositing step ispreferably at least 120° C., more preferably at least 140° C., even morepreferably at least 150° C., most preferably preferably at least 160° C.

The annealing temperature of the first depositing step is preferably atmost 250° C., more preferably at most 240° C., even more preferably atmost 230° C.

Specifically, the annealing temperature of the second depositing step ispreferably at most 250° C., more preferably at most 240° C., even morepreferably at most 230° C.

In a preferred embodiment, the annealing temperature of the thirddepositing step is preferably at most 200° C., more preferably at most190° C., even more preferably at most 180° C.

Preferably, at least one layer is crosslinked during the annealing inthe depositing step; more preferably at least two layers are crosslinkedduring the annealing in the depositing step.

As mentioned above, in the present method the HTL and the EML of atleast one pixel type are obtained by depositing inks. Inks arecompositions comprising a solvent and at least one functional organicmaterial being useful, e.g. for obtaining a HTL or EML as mentionedabove.

The viscosity of the solvent is in a range such that the solvent can beprocessed by usual printing techniques as mentioned above and below.Therefore, a solvent having a viscosity in the range from 0.1 to 2000mPas at the printing temperatures as mentioned above and below (e.g. 10°C., 15° C., 25° C., 40° C., 60° C. and 80° C., respectively) isconsidered liquid. The viscosity values are measured with a parallelplate rotational rheometer (AR-G2 or Discovery HR-3 TA Instruments) at asheer rate of 500 s⁻¹, unless stated otherwise.

Solvents are compounds being removed after the ink is applied to form alayer as mentioned above and below.

In a preferred embodiment, the solvent exhibits a viscosity in the rangefrom 0.5 to 50 mPas, more preferably from 1 to 20 mPas, even morepreferably from 2 to 15 mPas and most preferably from 3 to 10 mPas at25.0° C.

The viscosity of the solvents is measured with a with a parallel platerotational rheometer of the type Discovery HR3 (TA Instruments). Theequipment allows a precise control of the temperature and sheer rate.The measurement of the viscosity is carried out at a temperature of25.0° C. (+/−0.2° C.) and a sheer rate of 500 s⁻¹. Each sample ismeasured three times and the obtained measured values are averaged. Acertified standard viscosity oil is measured prior to measuring thesolvents.

Preferred organic solvents can exhibit Hansen Solubility parameters ofH_(d) in the range of 15.5 to 22.0 MPa^(0.5), H_(p) in the range of 0.0to 12.5 MPa^(0.5) and H_(h) in the range of 0.0 to 15.0 MPa^(0.5). Morepreferred first organic solvents exhibit Hansen Solubility parameters ofH_(d) in the range of 16.5 to 21.0 MPa^(0.5), H_(p) in the range of 0.0to 6.0 MPa^(0.5) and H_(h) in the range of 0.0 to 6.0 MPa^(0.5).

The Hansen Solubility Parameters can be determined according to theHansen Solubility Parameters in Practice HSPiP 4th edition, (Softwareversion 4.0.7) with reference to the Hansen Solubility Parameters: AUser's Handbook, Second Edition, C. M. Hansen (2007), Taylor and FrancisGroup, LLC) as supplied by Hanson and Abbot et al.

Preferably, the organic solvent has a boiling point of 400° C. or below,preferably in the range from 150° C. to 400° C., more preferably in therange from 200° C. to 350° C. and most preferably in the range from 240°C. to 300° C., wherein the boiling point is given at 760 mm Hg.

Suitable organic solvents are preferably solvents which include interalia aldehydes, ketones, ethers, esters, amides such asdi-C₁₋₂-alkyl-formamides, sulfur compounds, nitro compounds,hydrocarbons, halogenated hydrocarbons (e.g. chlorinated hydrocarbons),aromatic or heteroaromatic hydrocarbons, halogenated aromatic orheteroaromatic hydrocarbons, preferably ketones, ethers and esters.

Preferably, the organic solvent is selected from the group consisting ofsubstituted and non-substituted aromatic or linear esters such as ethylbenzoate, butyl benzoate; substituted and non-substituted aromatic orlinear ethers such as 3-phenoxytoluene or anisole derivatives;substituted or non-substituted arene derivatives such as xylene; indanederivatives such as hexamethylindane; substituted and non-substitutedaromatic or linear ketones; substituted and non-substituted heterocyclessuch as pyrrolidinones, pyridines; fluorinated or chlorinatedhydrocarbons; and linear or cyclic siloxanes.

Particularly preferred organic solvents are, for example,1,2,3,4-tetramethylbenzene, 1,2,3,5-tetramethylbenzene,1,2,3-trimethylbenzene, 1,2,4-trichlorobenzene, 1,2,4-trimethylbenzene,1,2-dihydronaphthalene, 1,2-dimethylnaphthalene, 1,3-benzodioxolane,1,3-diisopropylbenzene, 1,3-dimethylnaphthalene, 1,4-benzodioxane,1,4-diisopropylbenzene, 1,4-dimethylnaphthalene, 1,5-dimethyltetralin,1-benzothiophene, 1-bromonaphthalene, 1-chloromethylnaphthalene,1-ethylnaphthalene, 1-methoxynaphthalene, 1-methylnaphthalene,1-methylindole, 2,3-benzofuran, 2,3-dihydrobenzofuran,2,3-dimethylanisole, 2,4-dimethylanisole, 2,5-dimethylanisole,2,6-dimethylanisole, 2,6-dimethylnaphthalene,2-bromo-3-bromomethylnaphthalene, 2-bromomethylnaphthalene,2-bromonaphthalene, 2-ethoxynaphthalene, 2-ethylnaphthalene,2-isopropylanisole, 2-methylanisole, 2-methylindole,3,4-dimethylanisole, 3,5-dimethylanisole, 3-bromoquinoline,3-methylanisole, 4-methylanisole, 5-decanolide, 5-methoxyindane,5-methoxyindole, 5-tert-butyl-m-xylene, 6-methylquinoline,8-methylquinoline, acetophenone, anisole, benzonitrile, benzothiazole,benzyl acetate, bromobenzene, butyl benzoate, butyl phenyl ether,cyclohexylbenzene, decahydronaphthol, dimethoxytoluene,3-phenoxytoluene, diphenyl ether, propiophenone, ethylbenzene, ethylbenzoate, γ-terpinene, hexylbenzene, indane, hexamethylindane, indene,isochroman, cumene, m-cymene, mesitylene, methyl benzoate, o-, m-,p-xylene, propyl benzoate, propylbenzene, o-dichlorobenzene,pentylbenzene, phenetol, ethoxybenzene, phenyl acetate, p-cymene,propiophenone, sec-butylbenzene, t-butylbenzene, thiophene, toluene,veratrol, monochlorobenzene, o-dichlorobenzene, pyridine, pyrazine,pyrimidine, pyrrolidinone, morpholine, dimethylacetamide, dimethylsulfoxide, decaline and/or mixtures of these compounds.

These organic solvents can be employed individually or as a mixture oftwo, three or more solvents forming the organic solvent.

Preferably, the ink has preferably a surface tension in the range from 1to 70 mN/m, more preferably in the range from 10 to 60 mN/m, even morepreferably in the range from 20 to 50 mN/m and most preferably in therange from 30 to 45 mN/m.

The surface tension of the inks of the present invention is measured bypendant drop characterization which is an optical method. Thismeasurement technique dispenses a drop from a needle in a bulk gaseousphase. The shape of the drop results from the relationship between thesurface tension, gravity and density differences. Using the pendant dropmethod, the surface tension is calculated from the shadow image of apendant drop using drop shape analysis. A commonly used and commerciallyavailable high precision drop shape analysis tool, namely the FTA 1000from First Ten Angstrom, was used to perform all surface tensionmeasurements. The surface tension is determined by the software inaccordance with DIN 55660-1 (Version 2011-12). All measurements wereperformed at room temperature which is in the range between 22° C. and24° C., preferably 23.4° C. The standard operating procedure includesthe determination of the surface tension of each ink using a freshdisposable drop dispensing system (syringe and needle). Each drop ismeasured and for each ink a minimum of three drops are measured. Thefinal value is averaged over said measurements. The tool is regularlycross-checked against various liquids having well known surface tension.

Preferably, the ink has a viscosity in the range from 0.5 to 50 mPas,more preferably in the range from 1 to 20 mPas, even more preferably inthe range from 2 to 15 mPas and most preferably in the range from 3 to10 mPas at 25° C.

The viscosity of the inks useful for the present invention is measuredwith a parallel plate rotational rheometer of the type Discovery HR3 (TAInstruments). The equipment allows a precise control of the temperatureand sheer rate. The measurement of the viscosity is carried out at atemperature of 25.0° C. (+/−0.2° C.) and a sheer rate of 500 s⁻¹,according to DIN 1342-2 (Version 2003-11). Each sample is measured threetimes and the obtained measured values are averaged. A certifiedstandard viscosity oil is measured prior to measuring the solvents.

In an embodiment of the present invention, the ink deposited formanufacturing a layer comprises a solvent and an organic functionalmaterial wherein the organic functional material has a solubility in theorganic solvent of at least 1 g/l at 25° C., preferably at least 5 g/lat 25° C.

Preferably, the ink comprises at least 0.01% by weight, more preferablyat least 0.1% by weight and most preferably at least 0.2% by weight ofsaid organic functional material.

The content of the organic functional material in the ink is preferablyin the range from 0.01 to 25 weight-%, more preferably in the range from0.1 to 20 weight-% and most preferably in the range from 0.2 to 10weight-%, based on the total weight of the ink.

The ink useful for the present invention comprises at least one organicfunctional material which can be employed for the production offunctional layers of electronic devices. Organic functional materialsare generally the organic materials which are introduced between theanode and the cathode of an electronic device.

The organic functional material is preferably selected from the groupconsisting of organic conductors, organic semiconductors, organicfluorescent compounds, organic phosphorescent compounds, organiclight-absorbent compounds, organic light-sensitive compounds, organicphotosensitisation agents and other organic photoactive compounds,selected from organometallic complexes of transition metals, rareearths, lanthanides and actinides.

More preferably, the organic functional material is selected from thegroup consisting of fluorescent emitters, phosphorescent emitters, hostmaterials, matrix materials, exciton-blocking materials,electron-transport materials, electron-injection materials,hole-conductor materials, hole-injection materials, n-dopants,p-dopants, wide-band-gap materials, electron-blocking materials andhole-blocking materials. Even more preferably, the organic functionalmaterial is an organic semiconductor selected from the group consistingof hole-injecting, hole-transporting, emitting, electron-transportingand electron-injecting materials. Especially preferably, the organicfunctional material is an organic semiconductor selected from the groupconsisting of hole-injecting, hole-transporting, emitting andelectron-transporting materials.

In a specific embodiment, two layers of one pixel type are preferablymanufactured by depositing two inks and the inks deposited formanufacturing two layers comprise each an organic functional materialand the energy level difference of the organic functional materialcomprised by the first ink and the organic functional material comprisedby the second ink is at most 0.5 eV, preferably at most 0.3 eV.

Preferably, two layers of one pixel type are manufactured by depositingtwo inks and the inks deposited for manufacturing two layers compriseeach an organic functional material wherein the first layer is a HIL andthe second layer is a HTL and the energy level difference of thehole-injecting material comprised by the first ink and thehole-transporting material comprised by the second ink is at most 0.5eV, preferably at most 0.3 eV.

Furthermore, two layers of one pixel type are preferably manufactured bydepositing two inks and the inks deposited for manufacturing two layerscomprise each an organic functional material wherein the second layer isa HTL and the third layer is a EML and the energy level difference ofthe hole-transporting material comprised by the second ink and theemitting material comprised by the third ink is at most 0.5 eV,preferably at most 0.3 eV.

Preferred embodiments of organic functional materials are disclosed indetail in WO 2011/076314 A1 which is incorporated into the presentapplication by way of reference.

In a preferred embodiment, the organic functional material is selectedfrom the group consisting of fluorescent emitters and phosphorescentemitters.

The organic functional material can be a compound having a low molecularweight, a polymer, an oligomer or a dendrimer, where the organicfunctional material may also be in the form of a mixture. In a preferredembodiment the inks useful for the present invention may comprise twodifferent organic functional materials having a low molecular weight,one compound having a low molecular weight and one polymer or twopolymers (blend). In a further preferred embodiment the inks useful forthe present invention may comprise up to five different organicfunctional materials which are selected from compounds having a lowmolecular weight or from polymers.

Preferably, the organic functional material has a low molecular weight.A low molecular weight is a weight of ≤5,000 g/mol, preferably ≤3,000g/mol, more preferably ≤2,000 g/mol and most preferably ≤1,800 g/mol.

Organic functional materials are frequently described by the propertiesof their frontier orbitals, which are described in greater detail below.Molecular orbitals, in particular also the highest occupied molecularorbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), theirenergy levels and the energy of the lowest triplet state T₁ or of thelowest excited singlet state S₁ of the materials are determined viaquantum-chemical calculations. In order to calculate organic substanceswithout metals, firstly a geometry optimisation is carried out using the“Ground State/Semi-empirical/Default Spin/AM1/Charge 0/Spin Singlet”method. An energy calculation is subsequently carried out on the basisof the optimised geometry. The “TD-SCF/DFT/Default Spin/B3PW91” methodwith the “6-31G(d)” base set (charge 0, spin singlet) is used here. Formetal-containing compounds, the geometry is optimised via the “GroundState/Hartree-Fock/Default Spin/LanL2MB/Charge 0/Spin Singlet” method.The energy calculation is carried out analogously to the above-describedmethod for the organic substances, with the difference that the“LanL2DZ” base set is used for the metal atom and the “6-31G(d)” baseset is used for the ligands. The energy calculation gives the HOMOenergy level HEh or LUMO energy level LEh in hartree units. The HOMO andLUMO energy levels in electron volts calibrated with reference to cyclicvoltammetry measurements are determined therefrom as follows:

HOMO(eV)=((HEh*27.212)−0.9899)/1.1206

LUMO(eV)=((LEh*27.212)−2.0041)/1.385

For the purposes of this application, these values are to be regarded asHOMO and LUMO energy levels respectively of the materials.

The lowest triplet state T₁ is defined as the energy of the tripletstate having the lowest energy which arises from the quantum-chemicalcalculation described.

The lowest excited singlet state S₁ is defined as the energy of theexcited singlet state having the lowest energy which arises from thequantum-chemical calculation described.

The method described herein is independent of the software package usedand always gives the same results. Examples of frequently used programsfor this purpose are “Gaussian09W” (Gaussian Inc.) and Q-Chem 4.1(Q-Chem, Inc.).

Materials having hole-injection properties, also called hole-injectionmaterials herein, simplify or facilitate the transfer of holes, i.e.positive charges, from the anode into an organic layer. In general, ahole-injection material has an HOMO level which is in the region of orabove the Fermi level of the anode.

Compounds having hole-transport properties, also called hole-transportmaterials herein, are capable of transporting holes, i.e. positivecharges, which are generally injected from the anode or an adjacentlayer, for example a hole-injection layer. A hole-transport materialgenerally has a high HOMO level of preferably at least −5.4 eV.Depending on the structure of the electronic device, it may also bepossible to employ a hole-transport material as hole-injection material.

The preferred compounds which have hole-injection and/or hole-transportproperties include, for example, triarylamine, benzidine,tetraaryl-para-phenylenediamine, triarylphosphine, phenothiazine,phenoxazine, dihydrophenazine, thianthrene, dibenzo-para-dioxin,phenoxathiyne, carbazole, azulene, thiophene, pyrrole and furanderivatives and further O-, S- or N-containing heterocycles having ahigh HOMO (HOMO=highest occupied molecular orbital). Polymers such asPEDOT:PSS can also be used as compounds with hole-injection and/orhole-transport properties.

As compounds which have hole-injection and/or hole-transport properties,particular mention may be made of phenylenediamine derivatives (U.S.Pat. No. 3,615,404), arylamine derivatives (U.S. Pat. No. 3,567,450),amino-substituted chalcone derivatives (U.S. Pat. No. 3,526,501),styrylanthracene derivatives (JP-A-56-46234), polycyclic aromaticcompounds (EP 1009041), polyarylalkane derivatives (U.S. Pat. No.3,615,402), fluorenone derivatives (JP-A-54-110837), hydrazonederivatives (U.S. Pat. No. 3,717,462), acylhydrazones, stilbenederivatives (JP-A-61-210363), silazane derivatives (U.S. Pat. No.4,950,950), polysilanes (JP-A-2-204996), aniline copolymers(JP-A-2-282263), thiophene oligomers (JP Heisei 1 (1989) 211399),polythiophenes, poly(N-vinylcarbazole) (PVK), polypyrroles, polyanilinesand other electrically conducting macromolecules, porphyrin compounds(JP-A-63-2956965, U.S. Pat. No. 4,720,432), aromatic dimethylidene-typecompounds, carbazole compounds, such as, for example, CDBP, CBP, mCP,aromatic tertiary amine and styrylamine compounds (U.S. Pat. No.4,127,412), such as, for example, triphenylamines of the benzidine type,triphenylamines of the styrylamine type and triphenylamines of thediamine type. It is also possible to use arylamine dendrimers (JP Heisei8 (1996) 193191), monomeric triarylamines (U.S. Pat. No. 3,180,730),triarylamines containing one or more vinyl radicals and/or at least onefunctional group containing active hydrogen (U.S. Pat. Nos. 3,567,450and 3,658,520), or tetraaryldiamines (the two tertiary amine units areconnected via an aryl group). More triarylamino groups may also bepresent in the molecule. Phthalocyanine derivatives, naphthalocyaninederivatives, butadiene derivatives and quinoline derivatives, such as,for example, dipyrazino[2,3-f:2′,3′-h]quinoxalinehexacarbonitrile, arealso suitable.

Preference is given to aromatic tertiary amines containing at least twotertiary amine units (US 2008/0102311 A1, U.S. Pat. Nos. 4,720,432 and5,061,569), such as, for example, NPD(α-NPD=4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl) (U.S. Pat. No.5,061,569), TPD 232(=N,N′-bis-(N,N′-diphenyl-4-aminophenyl)-N,N-diphenyl-4,4′-diamino-1,1′-biphenyl)or MTDATA (MTDATA orm-MTDATA=4,4′,4″-tris[3-methylphenyl)phenylamino]-triphenylamine)(JP-A-4-308688), TBDB (=N,N,N′,N′-tetra(4-biphenyl)-diaminobiphenylene),TAPC (=1,1-bis(4-di-p-tolylaminophenyl)cyclohexane), TAPPP(=1,1-bis(4-di-p-tolylaminophenyl)-3-phenylpropane), BDTAPVB(=1,4-bis[2-[4-[N,N-di(p-tolyl)amino]phenyl]vinyl]benzene), TTB(=N,N,N′,N′-tetra-p-tolyl-4,4′-diaminobiphenyl), TPD(=4,4′-bis[N-3-methylphenyl]-N-phenylamino)biphenyl),N,N,N′,N′-tetraphenyl-4,4′″-diamino-1,1′,4′,1″,4″,1′″-quaterphenyl,likewise tertiary amines containing carbazole units, such as, forexample, TCTA(=4-(9H-carbazol-9-yl)-N,N-bis[4-(9H-carbazol-9-yl)phenyl]benzenamine).Preference is likewise given to hexaazatriphenylene compounds inaccordance with US 2007/0092755 A1 and phthalocyanine derivatives (forexample H₂Pc, CuPc (=copper phthalocyanine), CoPc, NiPc, ZnPc, PdPc,FePc, MnPc, ClAlPc, ClGaPc, ClInPc, ClSnPc, Cl₂SiPc, (HO)AlPc, (HO)GaPc,VOPc, TiOPc, MoOPc, GaPc-O—GaPc).

Particular preference is given to the following triarylamine compoundsof the formulae (TA-1) to (TA-12), which are disclosed in the documentsEP 1162193 B1, EP 650 955 B1, Synth. Metals 1997, 91(1-3), 209, DE19646119 A1, WO 2006/122630 A1, EP 1 860 097 A1, EP 1834945 A1, JP08053397 A, U.S. Pat. No. 6,251,531 B1, US 2005/0221124, JP 08292586 A,U.S. Pat. No. 7,399,537 B2, US 2006/0061265 A1, EP 1 661 888 and WO2009/041635. The said compounds of the formulae (TA-1) to (TA-12) mayalso be substituted:

Further compounds which can be employed as hole-injection materials aredescribed in EP 0891121 A1 and EP 1029909 A1, injection layers ingeneral in US 2004/0174116 A1.

These arylamines and heterocycles which are generally employed ashole-injection and/or hole-transport materials preferably result in anHOMO in the polymer of greater than −5.8 eV (vs. vacuum level),particularly preferably greater than −5.5 eV.

Compounds which have electron-injection and/or electron-transportproperties are, for example, pyridine, pyrimidine, pyridazine, pyrazine,oxadiazole, quinoline, quinoxaline, anthracene, benzanthracene, pyrene,perylene, benzimidazole, triazine, ketone, phosphine oxide and phenazinederivatives, but also triarylboranes and further O-, S- or N-containingheterocycles having a low LUMO (LUMO=lowest unoccupied molecularorbital).

Particularly suitable compounds for electron-transporting andelectron-injecting layers are metal chelates of 8-hydroxyquinoline (forexample LiQ, AlQ₃, GaQ₃, MgQ₂, ZnQ₂, InQ₃, ZrQ₄), BAlQ, Ga oxinoidcomplexes, 4-azaphenanthren-5-ol-Be complexes (U.S. Pat. No. 5,529,853A, cf. formula ET-1), butadiene derivatives (U.S. Pat. No. 4,356,429),heterocyclic optical brighteners (U.S. Pat. No. 4,539,507),benzimidazole derivatives (US 2007/0273272 A1), such as, for example,TPBI (U.S. Pat. No. 5,766,779, cf. formula ET-2), 1,3,5-triazines, forexample spirobifluorenyltriazine derivatives (for example in accordancewith DE 102008064200), pyrenes, anthracenes, tetracenes, fluorenes,spirofluorenes, dendrimers, tetracenes (for example rubrenederivatives), 1,10-phenanthroline derivatives (JP 2003-115387, JP2004-311184, JP-2001-267080, WO 02/043449), silacyclopentadienederivatives (EP 1480280, EP 1478032, EP 1469533), borane derivatives,such as, for example, triarylborane derivatives containing Si (US2007/0087219 A1, cf. formula ET-3), pyridine derivatives (JP2004-200162), phenanthrolines, especially 1,10-phenanthrolinederivatives, such as, for example, BCP and Bphen, also severalphenanthrolines connected via biphenyl or other aromatic groups(US-2007-0252517 A1) or phenanthrolines connected to anthracene (US2007-0122656 A1, cf. formulae ET-4 and ET-5).

Likewise suitable are heterocyclic organic compounds, such as, forexample, thiopyran dioxides, oxazoles, triazoles, imidazoles oroxadiazoles. Examples of the use of five-membered rings containing N,such as, for example, oxazoles, preferably 1,3,4-oxadiazoles, forexample compounds of the formulae ET-6, ET-7, ET-8 and ET-9, which aredisclose, inter alia, in US 2007/0273272 A1; thiazoles, oxadiazoles,thiadiazoles, triazoles, inter alia, see US 2008/0102311 A1 and Y. A.Levin, M. S. Skorobogatova, Khimiya Geterotsiklicheskikh Soedinenii 1967(2), 339-341, preferably compounds of the formula ET-10,silacyclopentadiene derivatives. Preferred compounds are the followingof the formulae (ET-6) to (ET-10):

It is also possible to employ organic compounds, such as derivatives offluorenone, fluorenylidenemethane, perylenetetracarbonic acid,anthraquinonedimethane, diphenoquinone, anthrone andanthraquinonediethylenediamine.

Preference is given to 2,9,10-substituted anthracenes (with 1- or2-naphthyl and 4- or 3-biphenyl) or molecules which contain twoanthracene units (US2008/0193796 A1, cf. formula ET-11). Also veryadvantageous is the connection of 9,10-substituted anthracene units tobenzimidazole derivatives (US 2006 147747 A and EP 1551206 A1, cf.formulae ET-12 and ET-13).

The compounds which are able to generate electron-injection and/orelectron-transport properties preferably result in an LUMO of less than−2.5 eV (vs. vacuum level), particularly preferably less than −2.7 eV.

n-Dopants herein are taken to mean reducing agents, i.e. electrondonors. Preferred examples of n-dopants are W(hpp)₄ and otherelectron-rich metal complexes in accordance with WO 2005/086251 A2, P═Ncompounds (for example WO 2012/175535 A1, WO 2012/175219 A1),naphthylenecarbodiimides (for example WO 2012/168358 A1), fluorenes (forexample WO 2012/031735 A1), free radicals and diradicals (for example EP1837926 A1, WO 2007/107306 A1), pyridines (for example EP 2452946 A1, EP2463927 A1), N-heterocyclic compounds (for example WO 2009/000237 A1)and acridines as well as phenazines (for example US 2007/145355 A1).

The inks useful for the present invention may comprise emitters. Theterm emitter denotes a material which, after excitation, which can takeplace by transfer of any type of energy, allows a radiative transitioninto a ground state with emission of light. In general, two classes ofemitter are known, namely fluorescent and phosphorescent emitters. Theterm fluorescent emitter denotes materials or compounds in which aradiative transition from an excited singlet state into the ground statetakes place. The term phosphorescent emitter preferably denotesluminescent materials or compounds which contain transition metals.

Emitters are frequently also called dopants if the dopants cause theproperties described above in a system. A dopant in a system comprisinga matrix material and a dopant is taken to mean the component whoseproportion in the mixture is the smaller. Correspondingly, a matrixmaterial in a system comprising a matrix material and a dopant is takento mean the component whose proportion in the mixture is the greater.Accordingly, the term phosphorescent emitter can also be taken to mean,for example, phosphorescent dopants.

Compounds which are able to emit light include, inter alia, fluorescentemitters and phosphorescent emitters. These include, inter alia,compounds containing stilbene, stilbenamine, styrylamine, coumarine,rubrene, rhodamine, thiazole, thiadiazole, cyanine, thiophene,paraphenylene, perylene, phtalocyanine, porphyrin, ketone, quinoline,imine, anthracene and/or pyrene structures. Particular preference isgiven to compounds which are able to emit light from the triplet statewith high efficiency, even at room temperature, i.e. exhibitelectrophosphorescence instead of electrofluorescence, which frequentlycauses an increase in the energy efficiency. Suitable for this purposeare firstly compounds which contain heavy atoms having an atomic numberof greater than 36. Preference is given to compounds which contain d- orf-transition metals which satisfy the above-mentioned condition.Particular preference is given here to corresponding compounds whichcontain elements from group 8 to 10 (Ru, Os, Rh, Ir, Pd, Pt). Suitablefunctional compounds here are, for example, various complexes, asdescribed, for example, in WO 02/068435 A1, WO 02/081488 A1, EP 1239526A2 and WO 2004/026886 A2.

Preferred compounds which can serve as fluorescent emitters aredescribed by way of example below. Preferred fluorescent emitters areselected from the class of the monostyrylamines, the distyrylamines, thetristyrylamines, the tetrastyrylamines, the styrylphosphines, the styrylethers and the arylamines.

A monostyrylamine is taken to mean a compound which contains onesubstituted or unsubstituted styryl group and at least one, preferablyaromatic, amine. A distyrylamine is taken to mean a compound whichcontains two substituted or unsubstituted styryl groups and at leastone, preferably aromatic, amine. A tristyrylamine is taken to mean acompound which contains three substituted or unsubstituted styryl groupsand at least one, preferably aromatic, amine. A tetrastyrylamine istaken to mean a compound which contains four substituted orunsubstituted styryl groups and at least one, preferably aromatic,amine. The styryl groups are particularly preferably stilbenes, whichmay also be further substituted. Corresponding phosphines and ethers aredefined analogously to the amines. An arylamine or an aromatic amine inthe sense of the present invention is taken to mean a compound whichcontains three substituted or unsubstituted aromatic or heteroaromaticring systems bonded directly to the nitrogen. At least one of thesearomatic or heteroaromatic ring systems is preferably a condensed ringsystem, preferably having at least 14 aromatic ring atoms. Preferredexamples thereof are aromatic anthracenamines, aromaticanthracenediamines, aromatic pyrenamines, aromatic pyrenediamines,aromatic chrysenamines or aromatic chrysenediamines. An aromaticanthracenamine is taken to mean a compound in which one diarylaminogroup is bonded directly to an anthracene group, preferably in the9-position. An aromatic anthracenediamine is taken to mean a compound inwhich two diarylamino groups are bonded directly to an anthracene group,preferably in the 2,6- or 9,10-position. Aromatic pyrenamines,pyrenediamines, chrysenamines and chrysenediamines are definedanalogously thereto, where the diarylamino groups are preferably bondedto the pyrene in the 1-position or in the 1,6-position.

Further preferred fluorescent emitters are selected fromindenofluorenamines or indenofluorenediamines, which are described,inter alia, in WO 2006/122630; benzoindenofluorenamines orbenzoindenofluorenediamines, which are described, inter alia, in WO2008/006449; and dibenzoindenofluorenamines ordibenzoindenofluorenediamines, which are described, inter alia, in WO2007/140847.

Examples of compounds from the class of the styrylamines which can beemployed as fluorescent emitters are substituted or unsubstitutedtristilbenamines or the dopants described in WO 2006/000388, WO2006/058737, WO 2006/000389, WO 2007/065549 and WO 2007/115610.Distyrylbenzene and distyrylbiphenyl derivatives are described in U.S.Pat. No. 5,121,029. Further styrylamines can be found in US 2007/0122656A1.

Particularly preferred styrylamine compounds are the compounds of theformula EM-1 described in U.S. Pat. No. 7,250,532 B2 and the compoundsof the formula EM-2 described in DE 10 2005 058557 A1:

Particularly preferred triarylamine compounds are compounds of theformulae EM-3 to EM-15 disclosed in CN 1583691 A, JP 08/053397 A andU.S. Pat. No. 6,251,531 B1, EP 1957606 A1, US 2008/0113101 A1, US2006/210830 A, WO 2008/006449 and DE 102008035413 and derivativesthereof:

Further preferred compounds which can be employed as fluorescentemitters are selected from derivatives of naphthalene, anthracene,tetracene, benzanthracene, benzophenanthrene (DE 10 2009 005746),fluorene, fluoranthene, periflanthene, indenoperylene, phenanthrene,perylene (US 2007/0252517 A1), pyrene, chrysene, decacyclene, coronene,tetraphenylcyclopentadiene, pentaphenylcyclopentadiene, fluorene,spirofluorene, rubrene, coumarine (U.S. Pat. Nos. 4,769,292, 6,020,078,US 2007/0252517 A1), pyran, oxazole, benzoxazole, benzothiazole,benzimidazole, pyrazine, cinnamic acid esters, diketopyrrolopyrrole,acridone and quinacridone (US 2007/0252517 A1).

Of the anthracene compounds, particular preference is given to9,10-substituted anthracenes, such as, for example,9,10-diphenylanthracene and 9,10-bis(phenylethynyl)anthracene.1,4-Bis(9′-ethynylanthracenyl)-benzene is also a preferred dopant.

Preference is likewise given to derivatives of rubrene, coumarine,rhodamine, quinacridone, such as, for example, DMQA(=N,N′-dimethylquinacridone), dicyanomethylenepyran, such as, forexample, DCM(=4-(dicyanoethylene)-6-(4-dimethylaminostyryl-2-methyl)-4H-pyran),thiopyran, polymethine, pyrylium and thiapyrylium salts, periflantheneand indenoperylene.

Blue fluorescent emitters are preferably polyaromatic compounds, suchas, for example, 9,10-di(2-naphthylanthracene) and other anthracenederivatives, derivatives of tetracene, xanthene, perylene, such as, forexample, 2,5,8,11-tetra-t-butylperylene, phenylene, for example4,4′-bis(9-ethyl-3-carbazovinylene)-1,1′-biphenyl, fluorene,fluoranthene, arylpyrenes (US 2006/0222886 A1), arylenevinylenes (U.S.Pat. Nos. 5,121,029, 5,130,603), bis-(azinyl)imine-boron compounds (US2007/0092753 A1), bis(azinyl)methene compounds and carbostyrylcompounds.

Further preferred blue fluorescent emitters are described in C. H. Chenet al.: “Recent developments in organic electroluminescent materials”Macromol. Symp. 125, (1997) 1-48 and “Recent progress of molecularorganic electroluminescent materials and devices” Mat. Sci. and Eng. R,39 (2002), 143-222.

Further preferred blue-fluorescent emitters are the hydrocarbonsdisclosed in DE 102008035413.

Preferred compounds which can serve as phosphorescent emitters aredescribed below by way of example.

Examples of phosphorescent emitters are revealed by WO 00/70655, WO01/41512, WO 02/02714, WO 02/15645, EP 1191613, EP 1191612, EP 1191614and WO 2005/033244. In general, all phosphorescent complexes as are usedin accordance with the prior art for phosphorescent OLEDs and as areknown to the person skilled in the art in the area of organicelectroluminescence are suitable, and the person skilled in the art willbe able to use further phosphorescent complexes without inventive step.

Phosphorescent metal complexes preferably contain Ir, Ru, Pd, Pt, Os orRe.

Preferred ligands are 2-phenylpyridine derivatives, 7,8-benzoquinolinederivatives, 2-(2-thienyl)pyridine derivatives, 2-(1-naphthyl)pyridinederivatives, 1-phenylisoquinoline derivatives, 3-phenylisoquinolinederivatives or 2-phenylquinoline derivatives. All these compounds may besubstituted, for example by fluoro, cyano and/or trifluoromethylsubstituents for blue. Auxiliary ligands are preferably acetylacetonateor picolinic acid.

Preferably, at least one of the organic semiconducting compounds is anorganic phosphorescent compound which emits light and in additioncontains at least one atom having an atomic number greater than 38.

Preferably, the phosphorescent compounds are compounds of formulae(EM-16) to (EM-19):

where

-   -   DCy is, identically or differently on each occurrence, a cyclic        group which contains at least one donor atom, preferably        nitrogen, carbon in the form of a carbene or phosphorus, via        which the cyclic group is bonded to the metal, and which may in        turn carry one or more substituents R^(a); the groups DCy and        CCy are connected to one another via a covalent bond;    -   CCy is, identically or differently on each occurrence, a cyclic        group which contains a carbon atom via which the cyclic group is        bonded to the metal and which may in turn carry one or more        substituents R^(a);    -   A is, identically or differently on each occurrence, a        monoanionic, bidentate chelating ligand, preferably a diketonate        ligand;    -   R^(a) are identically or differently at each instance, and are        F, Cl, Br, I, NO₂, CN, a straight-chain, branched or cyclic        alkyl or alkoxy group having from 1 to 20 carbon atoms, in which        one or more nonadjacent CH₂ groups may be replaced by —O—, —S—,        —NR^(b)—, —CONR^(b)—, —CO—O—, —C═O—, —CH═CH— or —C≡C—, and in        which one or more hydrogen atoms may be replaced by F, or an        aryl or heteroaryl group which has from 4 to 14 carbon atoms and        may be substituted by one or more R^(c) radicals, and a        plurality of substituents R^(a), either on the same ring or on        two different rings, may together in turn form a mono- or        polycyclic, aliphatic or aromatic ring system;    -   R^(b) are identically or differently at each instance, and are a        straight-chain, branched or cyclic alkyl or alkoxy group having        from 1 to 20 carbon atoms, in which one or more nonadjacent CH₂        groups may be replaced by —O—, —S—, —CO—O—, —C═O—, —CH═CH— or        —C≡C—, and in which one or more hydrogen atoms may be replaced        by F, or an aryl or heteroaryl group which has from 4 to 14        carbon atoms and may be substituted by one or more R^(c)        radicals; and    -   R^(c) are identically or differently at each instance, and are a        straight-chain, branched or cyclic alkyl or alkoxy group having        from 1 to 20 carbon atoms, in which one or more nonadjacent CH₂        groups may be replaced by —O—, —S—, —CO—O—, —C═O—, —CH═CH— or        —C≡C—, and in which one or more hydrogen atoms may be replaced        by F.

The groups as mentioned above are well known in the art. Additionalinformation are provided by the explizit examples as mentioned above andbelow. Furthermore, specific examples of the groups CCy, DCy, A, R^(a),R^(b) and R^(c) are provided, e.g. in the document WO2015018480A1 whichis expressly incorporated herein by reference for its disclosureregarding phosphorescent compounds.

In particular, complexes of Pt or Pd with tetradentate ligands of theformula EM-20 are suitable

The compounds of the formula EM-20 are described in greater detail in US2007/0087219 A1, where, for an explanation of the substituents andindices in the above formula, reference is made to this specificationfor disclosure purposes. Furthermore, Pt-porphyrin complexes having anenlarged ring system (US 2009/0061681 A1) and Ir complexes, for example2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin-Pt(II),tetraphenyl-Pt(II) tetrabenzoporphyrin (US 2009/0061681 A1),cis-bis(2-phenylpyridinato-N,C²′)Pt(II),cis-bis(2-(2′-thienyl)pyridinato-N,C³′)Pt(II),cis-bis(2-(2′-thienyl)-quinolinato-N,C⁵′)Pt(II),(2-(4,6-difluorophenyl)pyridinato-N,C²′)Pt(II) (acetylacetonate), ortris(2-phenylpyridinato-N,C²′)Ir(III) (=Ir(ppy)₃, green),bis(2-phenylpyridinato-N,C²)Ir(III) (acetylacetonate)(=Ir(ppy)₂acetylacetonate, green, US 2001/0053462 A1, Baldo, Thompson etal. Nature 403, (2000), 750-753),bis(1-phenylisoquinolinato-N,C²′)(2-phenylpyridinato-N,C²′)-iridium(III),bis(2-phenylpyridinato-N,C²′)(1-phenylisoquinolinato-N,C²′)-iridium(III),bis(2-(2′-benzothienyl)pyridinato-N,C³′)iridium(III) (acetylacetonate),bis(2-(4′,6′-difluorophenyl)pyridinato-N,C²′)iridium(III) (piccolinate)(Flrpic, blue), bis(2-(4′,6′-difluorophenyl)pyridinato-N,C²′)Ir(III)(tetrakis(1-pyrazolyl)borate),tris(2-(biphenyl-3-yl)-4-tert-butylpyridine)-iridium(III),(ppz)₂Ir(5phdpym) (US 2009/0061681 A1), (45ooppz)₂-Ir(5phdpym) (US2009/0061681 A1), derivatives of 2-phenylpyridine-Ir complexes, such as,for example, PQIr (=iridium(III)bis(2-phenylquinolyl-N,C²′)acetylacetonate),tris(2-phenylisoquinolinato-N,C)Ir(III) (red),bis(2-(2′-benzo[4,5-a]thienyl)pyridinato-N,C³)Ir (acetylacetonate)([Btp₂Ir(acac)], red, Adachi et al. Appl. Phys. Lett. 78 (2001),1622-1624).

Likewise suitable are complexes of trivalent lanthanides, such as, forexample, Tb³⁺ and Eu³⁺ (J. Kido et al. Appl. Phys. Lett. 65 (1994),2124, Kido et al. Chem. Lett. 657, 1990, US 2007/0252517 A1), orphosphorescent complexes of Pt(II), Ir(I), Rh(I) with maleonitriledithiolate (Johnson et al., JACS 105, 1983, 1795), Re(I)tricarbonyl-diimine complexes (Wrighton, JACS 96, 1974, 998, interalia), Os(II) complexes with cyano ligands and bipyridyl orphenanthroline ligands (Ma et al., Synth. Metals 94, 1998, 245).

Further phosphorescent emitters having tridentate ligands are describedin U.S. Pat. No. 6,824,895 and U.S. Ser. No. 10/729,238. Red-emittingphosphorescent complexes are found in U.S. Pat. Nos. 6,835,469 and6,830,828.

Particularly preferred compounds which are used as phosphorescentdopants are, inter alia, the compounds of the formula EM-21 described,inter alia, in US 2001/0053462 A1 and Inorg. Chem. 2001, 40(7),1704-1711, JACS 2001, 123(18), 4304-4312, and derivatives thereof.

Derivatives are described in U.S. Pat. Nos. 7,378,162 B2, 6,835,469 B2and JP 2003/253145 A.

Furthermore, the compounds of the formulae EM-22 to EM-25 described inU.S. Pat. No. 7,238,437 B2, US 2009/008607 A1 and EP 1348711, andderivatives thereof, can be employed as emitters.

Quantum dots can likewise be employed as emitters, these materials beingdisclosed in detail in WO 2011/076314 A1.

Compounds which are employed as host materials, in particular togetherwith emitting compounds, include materials from various classes ofsubstance.

Host materials generally have larger band gaps between HOMO and LUMOthan the emitter materials employed. In addition, preferred hostmaterials exhibit properties of either a hole- or electron-transportmaterial. Furthermore, host materials can have both electron- andhole-transport properties.

Host materials are in some cases also called matrix material, inparticular if the host material is employed in combination with aphosphorescent emitter in an OLED.

Preferred host materials or co-host materials, which are employed, inparticular, together with fluorescent dopants, are selected from theclasses of the oligoarylenes (for example2,2′,7,7-tetraphenylspirobifluorene in accordance with EP 676461 ordinaphthylanthracene), in particular the oligoarylenes containingcondensed aromatic groups, such as, for example, anthracene,benzanthracene, benzophenanthrene (DE 10 2009 005746, WO 2009/069566),phenanthrene, tetracene, coronene, chrysene, fluorene, spirofluorene,perylene, phthaloperylene, naphthaloperylene, decacyclene, rubrene, theoligoarylenevinylenes (for exampleDPVBi=4,4′-bis(2,2-diphenylethenyl)-1,1′-biphenyl or spiro-DPVBi inaccordance with EP 676461), the polypodal metal complexes (for examplein accordance with WO 04/081017), in particular metal complexes of8-hydroxyquinoline, for example AlQ₃ (=aluminium(III)tris(8-hydroxyquinoline)) orbis(2-methyl-8-quinolinolato)-4-(phenylphenolinolato)aluminium, alsowith imidazole chelate (US 2007/0092753 A1) and the quinoline-metalcomplexes, aminoquinoline-metal complexes, benzoquinoline-metalcomplexes, the hole-conducting compounds (for example in accordance withWO 2004/058911), the electron-conducting compounds, in particularketones, phosphine oxides, sulfoxides, etc. (for example in accordancewith WO 2005/084081 and WO 2005/084082), the atropisomers (for examplein accordance with WO 2006/048268), the boronic acid derivatives (forexample in accordance with WO 2006/117052) or the benzanthracenes (forexample in accordance with WO 2008/145239).

Particularly preferred compounds which can serve as host materials orco-host materials are selected from the classes of the oligoarylenes,comprising anthracene, benzanthracene and/or pyrene, or atropisomers ofthese compounds. An oligoarylene in the sense of the present inventionis intended to be taken to mean a compound in which at least three arylor arylene groups are bonded to one another.

Preferred host materials are selected, in particular, from compounds ofthe formula (H-1),

Ar⁴—(Ar⁵)_(p)—Ar⁶   (H-1)

where Ar⁴, Ar⁵, Ar⁶ are on each occurrence, identically or differently,an aryl or heteroaryl group having 5 to 30 aromatic ring atoms, whichmay optionally be substituted, and p represents an integer in the rangefrom 1 to 5; the sum of the π electrons in Ar⁴, Ar⁵ and Ar⁶ is at least30 if p=1 and at least 36 if p=2 and at least 42 if p=3.

In the compounds of the formula (H-1), the group Ar⁵ particularlypreferably stands for anthracene, and the groups Ar⁴ and Ar⁶ are bondedin the 9- and 10-position, where these groups may optionally besubstituted. Very particularly preferably, at least one of the groupsAr⁴ and/or Ar⁶ is a condensed aryl group selected from 1- or 2-naphthyl,2-, 3- or 9-phenanthrenyl or 2-, 3-, 4-, 5-, 6- or 7-benzanthracenyl.Anthracene-based compounds are described in US 2007/0092753 A1 and US2007/0252517 A1, for example2-(4-methylphenyl)-9,10-di-(2-naphthyl)anthracene,9-(2-naphthyl)-10-(1,1′-biphenyl)anthracene and9,10-bis[4-(2,2-diphenylethenyl)phenyl]anthracene,9,10-diphenylanthracene, 9,10-bis(phenylethynyl)anthracene and1,4-bis(9′-ethynylanthracenyl)benzene. Preference is also given tocompounds containing two anthracene units (US 2008/0193796 A1), forexample 10,10′-bis[1,1′,4′,1″]terphenyl-2-yl-9,9′-bisanthracenyl.

Further preferred compounds are derivatives of arylamine, styrylamine,fluorescein, diphenylbutadiene, tetraphenylbutadiene, cyclopentadiene,tetraphenylcyclopentadiene, pentaphenylcyclopentadiene, coumarine,oxadiazole, bisbenzoxazoline, oxazole, pyridine, pyrazine, imine,benzothiazole, benzoxazole, benzimidazole (US 2007/0092753 A1), forexample 2,2′,2″-(1,3,5-phenylene)tris[1-phenyl-1H-benzimidazole],aldazine, stilbene, styrylarylene derivatives, for example9,10-bis[4-(2,2-diphenylethenyl)phenyl]anthracene, and distyrylarylenederivatives (U.S. Pat. No. 5,121,029), diphenylethylene,vinylanthracene, diaminocarbazole, pyran, thiopyran,diketopyrrolopyrrole, polymethine, cinnamic acid esters and fluorescentdyes.

Particular preference is given to derivatives of arylamine andstyrylamine, for example TNB(=4,4′-bis[N-(1-naphthyl)-N-(2-naphthyl)amino]biphenyl). Metal-oxinoidcomplexes, such as LiQ or AlQ₃, can be used as co-hosts.

Preferred compounds with oligoarylene as matrix are disclosed in US2003/0027016 A1, U.S. Pat. No. 7,326,371 B2, US 2006/043858 A, WO2007/114358, WO 2008/145239, JP 3148176 B2, EP 1009044, US 2004/018383,WO 2005/061656 A1, EP 068101961, WO 2004/013073A1, U.S. Pat. No.5,077,142, WO 2007/065678 and DE 102009005746, where particularlypreferred compounds are described by the formulae H-2 to H-8.

Furthermore, compounds which can be employed as host or matrix includematerials which are employed together with phosphorescent emitters.

These compounds, which can also be employed as structural elements inpolymers, include CBP (N,N-biscarbazolylbiphenyl), carbazole derivatives(for example in accordance with WO 2005/039246, US 2005/0069729, JP2004/288381, EP 1205527 or WO 2008/086851), azacarbazoles (for examplein accordance with EP 1617710, EP 1617711, EP 1731584 or JP2005/347160), ketones (for example in accordance with WO 2004/093207 orin accordance with DE 102008033943), phosphine oxides, sulfoxides andsulfones (for example in accordance with WO 2005/003253),oligophenylenes, aromatic amines (for example in accordance with US2005/0069729), bipolar matrix materials (for example in accordance withWO 2007/137725), silanes (for example in accordance with WO2005/111172), 9,9-diarylfluorene derivatives (for example in accordancewith DE 102008017591), azaboroles or boronic esters (for example inaccordance with WO 2006/117052), triazine derivatives (for example inaccordance with DE 102008036982), indolocarbazole derivatives (forexample in accordance with WO 2007/063754 or WO 2008/056746),indenocarbazole derivatives (for example in accordance with DE102009023155 and DE 102009031021), diazaphosphole derivatives (forexample in accordance with DE 102009022858), triazole derivatives,oxazoles and oxazole derivatives, imidazole derivatives, polyarylalkanederivatives, pyrazoline derivatives, pyrazolone derivatives,distyrylpyrazine derivatives, thiopyran dioxide derivatives,phenylenediamine derivatives, tertiary aromatic amines, styrylamines,amino-substituted chalcone derivatives, indoles, hydrazone derivatives,stilbene derivatives, silazane derivatives, aromatic dimethylidenecompounds, carbodiimide derivatives, metal complexes of8-hydroxyquinoline derivatives, such as, for example, AlQ₃, which mayalso contain triarylaminophenol ligands (US 2007/0134514 A1), metalcomplex/polysilane compounds, and thiophene, benzothiophene anddibenzothiophene derivatives.

Examples of preferred carbazole derivatives are mCP(=1,3-N,N-dicarbazolylbenzene (=9,9′-(1,3-phenylene)bis-9H-carbazole))(formula H-9), CDBP(=9,9′-(2,2′-dimethyl[1,1′-biphenyl]-4,4′-diyl)bis-9H-carbazole),1,3-bis(N,N′-dicarbazolyl)benzene (=1,3-bis(carbazol-9-yl)benzene), PVK(polyvinylcarbazole), 3,5-di(9H-carbazol-9-yl)biphenyl and CMTTP(formula H-10). Particularly referred compounds are disclosed in US2007/0128467 A1 and US 2005/0249976 A1 (formulae H-11 and H-13).

Preferred tetraaryl-Si compounds are disclosed, for example, in US2004/0209115, US 2004/0209116, US 2007/0087219 A1 and in H. Gilman, E.A. Zuech, Chemistry & Industry (London, United Kingdom), 1960, 120.

Particularly preferred tetraaryl-Si compounds are described by theformulae H-14 to H-20.

Particularly preferred compounds from group 4 for the preparation of thematrix for phosphorescent dopants are disclosed, inter alia, in DE102009022858, DE 102009023155, EP 652273 B1, WO 2007/063754 and WO2008/056746, where particularly preferred compounds are described by theformulae H-22 to H-25.

With respect to the functional compounds which can be employed inaccordance with the invention and which can serve as host material,especial preference is given to substances which contain at least onenitrogen atom. These preferably include aromatic amines, triazinederivatives and carbazole derivatives. Thus, carbazole derivatives inparticular exhibit surprisingly high efficiency. Triazine derivativesresult in unexpectedly long lifetimes of the electronic devices.

It may also be preferred to employ a plurality of different matrixmaterials as a mixture, in particular at least one electron-conductingmatrix material and at least one hole-conducting matrix material.Preference is likewise given to the use of a mixture of acharge-transporting matrix material and an electrically inert matrixmaterial which is not in involved in the charge transport to asignificant extent, if at all, as described, for example, in WO2010/108579.

It is furthermore possible to employ compounds which improve thetransition from the singlet state to the triplet state and which,employed in support of the functional compounds having emitterproperties, improve the phosphorescence properties of these compounds.Suitable for this purpose are, in particular, carbazole and bridgedcarbazole dimer units, as described, for example, in WO 2004/070772 A2and WO 2004/113468 A1. Also suitable for this purpose are ketones,phosphine oxides, sulfoxides, sulfones, silane derivatives and similarcompounds, as described, for example, in WO 2005/040302 A1.

Furthermore, the inks may comprise a wide-band-gap material asfunctional material. Wide-band-gap material is taken to mean a materialin the sense of the disclosure content of U.S. Pat. No. 7,294,849. Thesesystems exhibit particularly advantageous performance data inelectroluminescent devices.

The compound employed as wide-band-gap material can preferably have aband gap of 2.5 eV or more, preferably 3.0 eV or more, particularlypreferably 3.5 eV or more. The band gap can be calculated, inter alia,by means of the energy levels of the highest occupied molecular orbital(HOMO) and the lowest unoccupied molecular orbital (LUMO).

Furthermore, the inks may comprise a hole-blocking material (HBM) asfunctional material. A hole-blocking material denotes a material whichprevents or minimises the transmission of holes (positive charges) in amultilayer system, in particular if this material is arranged in theform of a layer adjacent to an emission layer or a hole-conductinglayer. In general, a hole-blocking material has a lower HOMO level thanthe hole-transport material in the adjacent layer. Hole-blocking layersare frequently arranged between the light-emitting layer and theelectron-transport layer in OLEDs.

It is basically possible to employ any known hole-blocking material. Inaddition to other hole-blocking materials described elsewhere in thepresent application, advantageous hole-blocking materials are metalcomplexes (US 2003/0068528), such as, for example,bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminium(III) (BAlQ).Fac-tris(1-phenylpyrazolato-N,C2)-iridium(III) (Ir(ppz)₃) is likewiseemployed for this purpose (US 2003/0175553 A1). Phenanthrolinederivatives, such as, for example, BCP, or phthalimides, such as, forexample, TMPP, can likewise be employed.

Furthermore, advantageous hole-blocking materials are described in WO00/70655 A2, WO 01/41512 and WO 01/93642 A1.

Furthermore, the inks may comprise an electron-blocking material (EBM)as functional material. An electron-blocking material denotes a materialwhich prevents or minimises the transmission of electrons in amultilayer system, in particular if this material is arranged in theform of a layer adjacent to an emission layer or an electron-conductinglayer. In general, an electron-blocking material has a higher LUMO levelthan the electron-transport material in the adjacent layer.

It is basically possible to employ any known electron-blocking material.In addition to other electron-blocking materials described elsewhere inthe present application, advantageous electron-blocking materials aretransition-metal complexes, such as, for example, Ir(ppz)₃ (US2003/0175553).

The electron-blocking material can preferably be selected from amines,triarylamines and derivatives thereof.

Furthermore, the functional compounds which can be employed as organicfunctional materials in the inks preferably have, if they arelow-molecular-weight compounds, a molecular weight of ≤5,000 g/mol,preferably ≤3,000 g/mol, more preferably ≤2,000 g/mol and mostpreferably ≤1,800 g/mol.

Of particular interest are furthermore functional compounds which aredistinguished by a high glass-transition temperature. In thisconnection, particularly preferred functional compounds which can beemployed as organic functional material in the inks are those which havea glass-transition temperature of ≥70° C., preferably ≥100° C., morepreferably ≥125° C. and most preferably ≥150° C., determined inaccordance with DIN 51005 (Version 2005-08).

The inks may also comprise polymers as organic functional materials. Thecompounds described above as organic functional materials, whichfrequently have a relatively low molecular weight, can also be mixedwith a polymer. It is likewise possible to incorporate these compoundscovalently into a polymer. This is possible, in particular, withcompounds which are substituted by reactive leaving groups, such asbromine, iodine, chlorine, boronic acid or boronic acid ester, or byreactive, polymerisable groups, such as olefins or oxetanes. These canbe used as monomers for the production of corresponding oligomers,dendrimers or polymers. The oligomerisation or polymerisation herepreferably takes place via the halogen functionality or the boronic acidfunctionality or via the polymerisable group. It is furthermore possibleto crosslink the polymers via groups of this type. The compounds andpolymers according to the invention can be employed as crosslinked oruncrosslinked layer.

Polymers which can be employed as organic functional materialsfrequently contain units or structural elements which have beendescribed in the context of the compounds described above, inter aliathose as disclosed and extensively listed in WO 02/077060 A1, in WO2005/014689 A2 and in WO 2011/076314 A1. These are incorporated into thepresent application by way of reference. The functional materials canoriginate, for example, from the following classes:

-   -   Group 1: structural elements which are able to generate        hole-injection and/or hole-transport properties;    -   Group 2: structural elements which are able to generate        electron-injection and/or electron-transport properties;    -   Group 3: structural elements which combine the properties        described in relation to groups 1 and 2;    -   Group 4: structural elements which have light-emitting        properties, in particular phosphorescent groups;    -   Group 5: structural elements which improve the transition from        the so-called singlet state to the triplet state;    -   Group 6: structural elements which influence the morphology or        also the emission colour of the resultant polymers;    -   Group 7: structural elements which are typically used as        backbone.

The structural elements here may also have various functions, so that aclear assignment need not be advantageous. For example, a structuralelement of group 1 may likewise serve as backbone.

The polymer having hole-transport or hole-injection properties employedas organic functional material, containing structural elements fromgroup 1, may preferably contain units which correspond to thehole-transport or hole-injection materials described above.

Further preferred structural elements of group 1 are, for example,triarylamine, benzidine, tetraaryl-para-phenylenediamine, carbazole,azulene, thiophene, pyrrole and furan derivatives and further O-, S- orN-containing heterocycles having a high HOMO. These arylamines andheterocycles preferably have an HOMO of above −5.8 eV (against vacuumlevel), particularly preferably above −5.5 eV.

Preference is given, inter alia, to polymers having hole-transport orhole-injection properties, containing at least one of the followingrecurring units of the formula HTP-1:

in which the symbols have the following meaning:

-   -   Ar¹ is, in each case identically or differently for different        recurring units, a single bond or a monocyclic or polycyclic        aryl group, which may optionally be substituted;    -   Ar² is, in each case identically or differently for different        recurring units, a monocyclic or polycyclic aryl group, which        may optionally be substituted;    -   Ar³ is, in each case identically or differently for different        recurring units, a monocyclic or polycyclic aryl group, which        may optionally be substituted;    -   m is 1, 2 or 3.

Particular preference is given to recurring units of the formula HTP-1which are selected from the group consisting of units of the formulaeHTP-1A to HTP-1C:

in which the symbols have the following meaning:

-   -   R^(a) is on each occurrence, identically or differently, H, a        substituted or unsubstituted aromatic or heteroaromatic group,        an alkyl, cycloalkyl, alkoxy, aralkyl, aryloxy, arylthio,        alkoxycarbonyl, silyl or carboxyl group, a halogen atom, a cyano        group, a nitro group or a hydroxyl group;    -   r is 0, 1, 2, 3 or 4, and    -   s is 0, 1, 2, 3, 4 or 5.

Preference is given, inter alia, to polymers having hole-transport orhole-injection properties, containing at least one of the followingrecurring units of the formula HTP-2:

-(T¹)_(c)-(Ar⁷)_(d)-(T²)_(e)-(Ar⁸)_(f)—  HTP-2

in which the symbols have the following meaning:

T¹ and T² are selected independently from thiophene, selenophene,thieno-[2,3-b]thiophene, thieno[3,2-b]thiophene, dithienothiophene,pyrrole and aniline, where these groups may be substituted by one ormore radicals R^(b);

R^(b) is selected independently on each occurrence from halogen, —CN,—NC, —NCO, —NCS, —OCN, —SCN, —C(═O)NR⁰R⁰⁰, —C(═O)X, —C(═O)R⁰, —NH₂,—NR⁰R⁰⁰, —SH, —SR⁰, —SO₃H, —SO₂R⁰, —OH, —NO₂, —CF₃, —SF₅, an optionallysubstituted silyl, carbyl or hydrocarbyl group having 1 to 40 carbonatoms, which may optionally be substituted and may optionally containone or more heteroatoms;

R⁰ and R⁰⁰ are each independently H or an optionally substituted carbylor hydrocarbyl group having 1 to 40 carbon atoms, which may optionallybe substituted and may optionally contain one or more heteroatoms;

Ar⁷ and Ar⁸ represent, independently of one another, a monocyclic orpolycyclic aryl or heteroaryl group, which may optionally be substitutedand may optionally be bonded to the 2,3-position of one or both adjacentthiophene or selenophene groups;

c and e are, independently of one another, 0, 1, 2, 3 or 4, where1<c+e≤6;

d and f are, independently of one another, 0, 1, 2, 3 or 4.

Preferred examples of polymers having hole-transport or hole-injectionproperties are described, inter alia, in WO 2007/131582 A1 and WO2008/009343 A1.

The polymer having electron-injection and/or electron-transportproperties employed as organic functional material, containingstructural elements from group 2, may preferably contain units whichcorrespond to the electron-injection and/or electron-transport materialsdescribed above.

Further preferred structural elements of group 2 which haveelectron-injection and/or electron-transport properties are derived, forexample, from pyridine, pyrimidine, pyridazine, pyrazine, oxadiazole,quinoline, quinoxaline and phenazine groups, but also triarylboranegroups or further O-, S- or N-containing heterocycles having a low LUMOlevel. These structural elements of group 2 preferably have an LUMO ofbelow −2.7 eV (against vacuum level), particularly preferably below −2.8eV.

The organic functional material can preferably be a polymer whichcontains structural elements from group 3, where structural elementswhich improve the hole and electron mobility (i.e. structural elementsfrom groups 1 and 2) are connected directly to one another. Some ofthese structural elements can serve as emitters here, where the emissioncolours may be shifted, for example, into the green, red or yellow.Their use is therefore advantageous, for example, for the generation ofother emission colours or a broad-band emission by polymers whichoriginally emit in blue.

The polymer having light-emitting properties employed as organicfunctional material, containing structural elements from group 4, maypreferably contain units which correspond to the emitter materialsdescribed above. Preference is given here to polymers containingphosphorescent groups, in particular the emitting metal complexesdescribed above which contain corresponding units containing elementsfrom groups 8 to 10 (Ru, Os, Rh, Ir, Pd, Pt).

The polymer employed as organic functional material containing units ofgroup 5 which improve the transition from the so-called singlet state tothe triplet state can preferably be employed in support ofphosphorescent compounds, preferably the polymers containing structuralelements of group 4 described above. A polymeric triplet matrix can beused here.

Suitable for this purpose are, in particular, carbazole and connectedcarbazole dimer units, as described, for example, in DE 10304819 A1 andDE 10328627 A1. Also suitable for this purpose are ketone, phosphineoxide, sulfoxide, sulfone and silane derivatives and similar compounds,as described, for example, in DE 10349033 A1. Furthermore, preferredstructural units can be derived from compounds which have been describedabove in connection with the matrix materials employed together withphosphorescent compounds.

The further organic functional material is preferably a polymercontaining units of group 6 which influence the morphology and/or theemission colour of the polymers. Besides the polymers mentioned above,these are those which have at least one further aromatic or anotherconjugated structure which do not count amongst the above-mentionedgroups. These groups accordingly have only little or no effect on thecharge-carrier mobilities, the non-organometallic complexes or thesinglet-triplet transition.

The polymers may also include cross-linkable groups such as styrene,benzocyclobutene, epoxide and oxetane moieties.

Structural units of this type are able to influence the morphologyand/or the emission colour of the resultant polymers. Depending on thestructural unit, these polymers can therefore also be used as emitters.

In the case of fluorescent OLEDs, preference is therefore given toaromatic structural elements having 6 to 40 C atoms or also tolan,stilbene or bis-styrylarylene derivative units, each of which may besubstituted by one or more radicals. Particular preference is given hereto the use of groups derived from 1,4-phenylene, 1,4-naphthylene, 1,4-or 9,10-anthrylene, 1,6-, 2,7- or 4,9-pyrenylene, 3,9- or3,10-perylenylene, 4,4′-biphenylene, 4,4″-terphenylylene,4,4′-bi-1,1′-naphthylylene, 4,4′-tolanylene, 4,4′-stilbenylene or4,4″-bisstyrylarylene derivatives.

The polymer employed as organic functional material preferably containsunits of group 7, which preferably contain aromatic structures having 6to 40 C atoms which are frequently used as backbone.

These include, inter alia, 4,5-dihydropyrene derivatives,4,5,9,10-tetrahydropyrene derivatives, fluorene derivatives, which aredisclosed, for example, in U.S. Pat. No. 5,962,631, WO 2006/052457 A2and WO 2006/1 18345A1, 9,9-spirobifluorene derivatives, which aredisclosed, for example, in WO 2003/020790 A1, 9,10-phenanthrenederivatives, which are disclosed, for example, in WO 2005/104264 A1,9,10-dihydrophenanthrene derivatives, which are disclosed, for example,in WO 2005/014689 A2, 5,7-dihydrodibenzoxepine derivatives and cis- andtrans-indenofluorene derivatives, which are disclosed, for example, inWO 2004/041901 A1 and WO 2004/113412 A2, and binaphthylene derivatives,which are disclosed, for example, in WO 2006/063852 A1, and furtherunits which are disclosed, for example, in WO 2005/056633 A1, EP 1344788A1, WO 2007/043495 A1, WO 2005/033174 A1, WO 2003/099901 A1 and DE102006003710.

Particular preference is given to structural units of group 7 which areselected from fluorene derivatives, which are disclosed, for example, inU.S. Pat. No. 5,962,631, WO 2006/052457 A2 and WO 2006/118345 A1,spiro-bifluorene derivatives, which are disclosed, for example, in WO2003/020790 A1, benzofluorene, dibenzofluorene, benzothiophene anddibenzofluorene groups and derivatives thereof, which are disclosed, forexample, in WO 2005/056633 A1, EP 1344788 A1 and WO 2007/043495 A1.

Especially preferred structural elements of group 7 are represented bythe general formula PB-1:

in which the symbols and indices have the following meanings:

A, B and B′ are each, also for different recurring units, identically ordifferently, a divalent group, which is preferably selected from—CR^(c)R^(d)—, —NR^(c)—, —PR^(c)—, —O—, —S—, —SO—, —SO₂—, —CO—, —CS—,—CSe—, —P(═O)R^(c)—, —P(═S)R^(c)— and —SiR^(c)R^(d)—;

R^(c) and R^(d) are selected on each occurrence, independently, from H,halogen, —CN, —NC, —NCO, —NCS, —OCN, —SCN, —C(═O)NR⁰R⁰⁰, —C(═O)X,—C(═O)R⁰, —NH₂, —NR⁰R⁰⁰, —SH, —SR⁰, —SO₃H, —SO₂R⁰, —OH, —NO₂, —CF₃,—SF₅, an optionally substituted silyl, carbyl or hydrocarbyl grouphaving 1 to 40 carbon atoms, which may optionally be substituted and mayoptionally contain one or more heteroatoms, where the groups R^(c) andR^(d) may optionally form a spiro group with a fluorene radical to whichthey are bonded; X is halogen;

R⁰ and R⁰⁰ are each, independently, H or an optionally substitutedcarbyl or hydrocarbyl group having 1 to 40 carbon atoms, which mayoptionally be substituted and may optionally contain one or moreheteroatoms;

g is in each case, independently, 0 or 1 and h is in each case,independently, 0 or 1, where the sum of g and h in a sub-unit ispreferably 1;

m is an integer≥1;

Ar¹ and Ar² represent, independently of one another, a monocyclic orpolycyclic aryl or heteroaryl group, which may optionally be substitutedand may optionally be bonded to the 7,8-position or the 8,9-position ofan indenofluorene group;

a and b are, independently of one another, 0 or 1.

If the groups R^(c) and R^(d) form a spiro group with the fluorene groupto which these groups are bonded, this group preferably represents aspiro-bifluorene.

Particular preference is given to recurring units of the formula PB-1which are selected from the group consisting of units of the formulaePB-1A to PB-1E:

where R^(c) has the meaning described above for formula PB-1, r is 0, 1,2, 3 or 4, and R^(e) has the same meaning as the radical R^(c).

R^(e) is preferably —F, —Cl, —Br, —I, —CN, —NO₂, —NCO, —NCS, —OCN, —SCN,—C(═O)NR⁰R⁰⁰, —C(═O)X, —C(═O)R⁰, —NR⁰R⁰⁰, an optionally substitutedsilyl, aryl or heteroaryl group having 4 to 40, preferably 6 to 20, Catoms, or a straight-chain, branched or cyclic alkyl, alkoxy,alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxygroup having 1 to 20, preferably 1 to 12, C atoms, where one or morehydrogen atoms may optionally be substituted by F or Cl, and the groupsR⁰, R⁰⁰ and X have the meaning described above for formula PB-1.

Particular preference is given to recurring units of the formula PB-1which are selected from the group consisting of units of the formulaePB-1F to PB-1I:

in which the symbols have the following meaning:

L is H, halogen or an optionally fluorinated, linear or branched alkylor alkoxy group having 1 to 12 C atoms and preferably stands for H, F,methyl, i-propyl, t-butyl, n-pentoxy or trifluoromethyl; and

L′ is an optionally fluorinated, linear or branched alkyl or alkoxygroup having 1 to 12 C atoms and preferably stands for n-octyl orn-octyloxy.

For carrying out the present invention, preference is given to polymerswhich contain more than one of the structural elements of groups 1 to 7described above. It may furthermore be provided that the polymerspreferably contain more than one of the structural elements from onegroup described above, i.e. comprise mixtures of structural elementsselected from one group.

Particular preference is given, in particular, to polymers which,besides at least one structural element which has light-emittingproperties (group 4), preferably at least one phosphorescent group,additionally contain at least one further structural element of groups 1to 3, 5 or 6 described above, where these are preferably selected fromgroups 1 to 3.

The proportion of the various classes of groups, if present in thepolymer, can be in broad ranges, where these are known to the personskilled in the art. Surprising advantages can be achieved if theproportion of one class present in a polymer, which is in each caseselected from the structural elements of groups 1 to 7 described above,is preferably in each case ≥5 mol %, particularly preferably in eachcase ≥10 mol %.

The preparation of white-emitting copolymers is described in detail,inter alia, in DE 10343606 A1.

In order to improve the solubility, the polymers may containcorresponding groups. It may preferably be provided that the polymerscontain substituents, so that on average at least 2 non-aromatic carbonatoms, particularly preferably at least 4 and especially preferably atleast 8 non-aromatic carbon atoms are present per recurring unit, wherethe average relates to the number average. Individual carbon atoms heremay be replaced, for example, by O or S. However, it is possible for acertain proportion, optionally all recurring units, to contain nosubstituents which contain non-aromatic carbon atoms. Short-chainsubstituents are preferred here, since long-chain substituents can haveadverse effects on layers which can be obtained using organic functionalmaterials. The substituents preferably contain at most 12 carbon atoms,preferably at most 8 carbon atoms and particularly preferably at most 6carbon atoms in a linear chain.

The polymer employed in accordance with the invention as organicfunctional material can be a random, alternating or regioregularcopolymer, a block copolymer or a combination of these copolymer forms.

In a further embodiment, the polymer employed as organic functionalmaterial can be a non-conjugated polymer having side chains, where thisembodiment is particularly important for phosphorescent OLEDs based onpolymers. In general, phosphorescent polymers can be obtained byfree-radical copolymerisation of vinyl compounds, where these vinylcompounds contain at least one unit having a phosphorescent emitterand/or at least one charge-transport unit, as is disclosed, inter alia,in U.S. Pat. No. 7,250,226 B2. Further phosphorescent polymers aredescribed, inter alia, in JP 2007/211243 A2, JP 2007/197574 A2, U.S.Pat. No. 7,250,226 B2 and JP 2007/059939 A.

In a further preferred embodiment, the non-conjugated polymers containbackbone units, which are connected to one another by spacer units.Examples of such triplet emitters which are based on non-conjugatedpolymers based on backbone units are disclosed, for example, in DE102009023154.

In a further preferred embodiment, the non-conjugated polymer can bedesigned as fluorescent emitter. Preferred fluorescent emitters whichare based on non-conjugated polymers having side chains containanthracene or benzanthracene groups or derivatives of these groups inthe side chain, where these polymers are disclosed, for example, in JP2005/108556, JP 2005/285661 and JP 2003/338375.

These polymers can frequently be employed as electron- or hole-transportmaterials, where these polymers are preferably designed asnon-conjugated polymers.

Furthermore, the functional compounds employed as organic functionalmaterials in the inks preferably have, in the case of polymericcompounds, a molecular weight M_(w) of preferably ≥10,000 g/mol, morepreferably ≥20,000 g/mol and most preferably ≥50,000 g/mol.

The molecular weight M_(w) of the polymers here is preferably in therange from 10,000 to 2,000,000 g/mol, more preferably in the range from20,000 to 1,000,000 g/mol and most preferably in the range from 50,000to 300,000 g/mol. The molecular weight M_(w) is determined by means ofGPC (=gel permeation chromatography) against an internal polystyrenestandard.

The publications cited above for description of the functional compoundsare incorporated into the present application by way of reference fordisclosure purposes.

The inks useful for the invention may comprise all organic functionalmaterials which are necessary for the production of the respectivefunctional layer of the electronic device. If, for example, ahole-transport, hole-injection, electron-transport or electron-injectionlayer is built up precisely from one functional compound, the inkcomprises precisely this compound as organic functional material. If anemission layer comprises, for example, an emitter in combination with amatrix or host material, the ink comprises, as organic functionalmaterial, precisely the mixture of emitter and matrix or host material,as described in greater detail elsewhere in the present application.

Besides the said components, the inks useful for the invention maycomprise further additives and processing assistants. These include,inter alia, surface-active substances (surfactants), lubricants andgreases, additives which modify the viscosity, additives which increasethe conductivity, dispersants, hydrophobicising agents, adhesionpromoters, flow improvers, antifoams, deaerating agents, diluents, whichmay be reactive or unreactive, fillers, assistants, processingassistants, dyes, pigments, stabilisers, sensitisers, nanoparticles andinhibitors.

Preference is furthermore also given to solutions of non-conducting,electronically inert polymers (matrix polymers; inert polymeric binders)which comprise admixed low-molecular-weight, oligomeric, dendritic,linear or branched and/or polymeric organic and/or organometallicsemiconductors. Preferably, the ink may comprise 0.1 to 10% morepreferably 0.25 to 5% most preferably 0.3 to 3% by weight inertpolymeric binders, based on the total weight of the ink.

Improvements can be achieved with volatile wetting agents. The term“volatile” as used above and below means that the agent can be removedfrom the organic semiconducting materials by evaporation, after thesematerials have been deposited onto a substrate of an OE device, underconditions (like temperature and/or reduced pressure) that do notsignificantly damage these materials or the OE device. Preferably thismeans that the wetting agent has a boiling point or sublimationtemperature of <350° C., more preferably ≤300° C., most preferably ≤250°C., at the pressure employed, very preferably at atmospheric pressure(1013 hPa). Evaporation can also be accelerated e.g. by applying heatand/or reduced pressure. Preferably, the wetting agents are not capableof chemically reacting with the functional materials. In particular theyare selected from compounds that do not have a permanent doping effecton the functional materials (e.g. by oxidising or otherwise chemicallyreacting with the functional materials). Therefore, the ink preferablyshould not contain additives, like e.g. oxidants or protonic or lewisacids, which react with the functional materials by forming ionicproducts.

Positive effects can be accomplished by inks comprising volatilecomponents having similar boiling points. Preferably, the difference ofthe boiling point of the wetting agent and the first organic solvent isin the range of −100° C. to 100° C., more preferably in the range of−70° C. to 70° C. and most preferably in the range of −50° C. to 50° C.If a mixture of two or more first organic solvents is used meeting therequirements as mentioned above in connection with the description ofthe first organic solvent, the boiling point of the lowest boiling firstorganic solvent is deciding.

Preferred wetting agents are aromatic or non-aromatic compounds. Withfurther preference the wetting agents are non-ionic compounds.Particular useful wetting agents comprise a surface tension of at most35 mN/m, preferably of at most 30 mN/m, and more preferably of at most25 mN/m. The surface tension can be measured using a FTA (First TenAngstrom) 1000 contact angle goniometer at 25° C. Details of the methodare available from First Ten Angstrom as published by Roger P. Woodward,Ph.D. “Surface Tension Measurements Using the Drop Shape Method”.Preferably, the pendant drop method can be used to determine the surfacetension.

According to a special aspect of the present invention, the differenceof the surface tension of the organic solvent and the wetting agent ispreferably at least 1 mN/m, more preferably at least 5 mN/m and mostpreferably at least 10 mN/m.

Improvements can be achieved by wetting agents comprising a molecularweight of at least 100 g/mol, preferably at least 150 g/mol, morepreferably at least 180 g/mol and most preferably at least 200 g/mol.

Suitable and preferred wetting agents that do not oxidise or otherwisechemically react with the organic functional materials, preferablyorganic semiconductor materials, are selected from the group consistingof siloxanes, alkanes, amines, alkenes, alkynes, alcohols and/orhalogenated derivates of these compounds. Furthermore, fluoro ethers,fluoro esters and/or fluoro ketones can be used. More preferably, thesecompounds are selected from cyclic siloxanes and methyl siloxanes having6 to 20 carbon atoms, especially 8 to 16 carbon atoms; C₇-C₁₄ alkanes,C₇-C₁₄ alkenes, C₇-C₁₄ alkynes, alcohols having 7 to 14 carbon atoms,fluoro ethers having 7 to 14 carbon atoms, fluoro esters having 7 to 14carbon atoms and fluoro ketones having 7 to 14 carbon atoms. Mostpreferred wetting agents are cyclic siloxanes and methyl siloxaneshaving 8 to 14 carbon atoms.

Useful and preferred alkanes having 7 to 14 carbon atoms includeheptane, octane, nonane, decane, undecane, dodecane, tridecane,tetradecane, 3-methyl heptane, 4-ethyl heptane, 5-propyl decane,trimethyl cyclohexane and decalin.

Halogenated alkanes having 7 to 14 carbon atoms include 1-chloroheptane, 1,2-dichloro octane, tetrafluoro octane, decafluoro dodecane,perfluoro nonane, 1,1,1-trifluoromethyl decane, and perfluoro methyldecalin.

Useful and preferred alkenes having 7 to 14 carbon atoms includeheptene, octene, nonene, 1-decene, 4-decene, undecene, dodecene,tridecene, tetradecene, 3-methyl heptene, 4-ethyl heptene, 5-propyldecene, and trimethyl cyclohexene.

Halogenated alkenes having 7 to 14 carbon atoms include 1,2-dichlorooctene, tetrafluoro octene, decafluoro dodecene, perfluoro nonene, and1,1,1-trifluoromethyl decene.

Useful and preferred alkynes having 7 to 14 carbon atoms include octyne,nonyne, 1-decyne, 4-decyne, dodecyne, tetradecyne, 3-methyl heptyne,4-ethyl heptyne, 5-propyl decyne, and trimethyl cyclohexyne.

Halogenated alkynes having 7 to 14 carbon atoms include 1,2-dichlorooctyne, tetrafluoro octyne, decafluoro dodecyne, perfluoro nonyne, and1,1,1-trifluoromethyl decyne.

Useful and preferred alcanols having 7 to 14 carbon atoms include,heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol,tetradecanol, 3-methyl heptanol, 3,5-dimethyl-1-hexyn-3-ol, 4-ethylheptanol, 5-propyl decanol, trimethyl cyclohexanol and hydroxyl decalin.

Halogenated alkanols having 7 to 14 carbon atoms include 1-chloroheptanol, 1,2-dichloro octanol, tetrafluoro octanol, decafluorododecanol, perfluoro nonanol, 1,1,1-trifluoromethyl decanol, and2-trifluoro methyl-1-hydroxy decalin.

Useful and preferred fluoro ethers having 7 to 14 carbon atoms include3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6 dodecafluoro-2-trifluoromethyl-hexane,3-propoxy-1,1,1,2,3,4,4,5,5,6,6,6 dodecafluoro-2-trifluoromethyl-hexane,and 3-propoxy-1,1,1,2,3,4,4,5,5,5 decafluoro-2-trifluoromethyl-pentane.

Useful and preferred fluoro esters having 7 to 14 carbon atoms include3-(1,1,1,2,3,4,4,5,5,6,6,6 dodecafluoro-2-trifluoromethyl-hexyl)ethanoate, and 3-(1,1,1,2,3,4,4,5,5,5decafluoro-2-trifluoromethyl-pentyl) propanoate.

Useful and preferred fluoro ketones having 7 to 14 carbon atoms include3-(1,1,1,2,3,4,4,5,5,6,6,6 dodecafluoro-2-trifluoromethyl-hexyl) ethylketone, and 3-(1,1,1,2,3,4,4,5,5,5 decafluoro-2-trifluoromethyl-pentyl)propyl ketone.

Useful and preferred siloxanes include hexamethyl disiloxane, octamethyltrisiloxane, decamethyl tetrasiloxane, dodecamethyl pentasiloxane,tetradecamethyl hexasiloxane, Octamethylcyclotetrasiloxane (CAS:556-67-2), Decamethylcyclopentasiloxane (CAS: 541-02-6),Dodecamethylcyclohexasiloxane (CAS: 540-97-6),Tetradecamethylcycloheptasiloxane (CAS: 107-50-6),Hexaethylcyclotrisiloxane (CAS: 2031-79-0), Octaethylcyclotetrasiloxane(CAS: 1451-99-6),2,4,6,8,10-pentaethyl-2,4,6,8,10-pentamethylcyclopentasiloxane (CAS:17940-63-5), and 2,4,6-triethyl-2,4,6-trimethylcyclotrisiloxane (CAS:15901-49-2).

Preferably, the ink may comprise at most 5% by weight, preferably atmost 2% by weight of wetting additives. Preferably, the ink comprises0.01 to 5% by weight, more preferably 0.1 to 2% by weight of wettingagent, based on the total weight of the ink.

The ink useful for the present invention can be designed as an emulsion,dispersion or solution. Preferably, the present ink is a solution(homogeneous mixture) comprising no considerable amounts of a secondphase.

In a preferred embodiment of the present invention, in a first step aHIL is formed, in a second step a HTL is formed and in a third step aEML is formed wherein the HIL is formed before the HTL and the HTL isformed before the EML.

The inks useful for preparing the functional layers can be applied, forexample, by slot-die coating, curtain coating, flood coating, dipcoating, spray coating, spin coating, screen printing, relief printing,gravure printing, rotary printing, roller coating, flexographicprinting, offset printing or nozzle printing, preferably inkjet printingon a substrate or one of the layers applied to the substrate.Preferably, at least one layer being obtained by depositing an ink isinkjet-printed, more preferably at least two layers being obtained bydepositing an ink are inkjet-printed. Inkjet printing is most preferred.Preferably, the inkjet-printed layer comprises a light emitting materialand/or a hole-transporting material.

After the application of an ink to a substrate or a functional layeralready applied, a drying step can be carried out in order to remove thesolvent from the applied, preferably inkjet-printed ink. Preferably, theinks are dried before the annealing step is performed and the dryingstep is performed under reduced pressure. Preferably, the dryingtemperature is below 150° C., preferably below 100° C., more preferablybelow 70° C. and most preferably below 40° C.

The drying can preferably be carried out at relatively low temperaturesuch as room temperature and over a relatively long period in order toavoid bubble formation and to obtain a uniform coating. Preferably, thedrying is carried out at a pressure in the range from 10⁻⁶ mbar to 1bar, particularly preferably in the range from 10⁻⁶ mbar to 100 mbar andespecially preferably in the range from 10⁻⁶ mbar to 10 mbar. Theduration of the drying depends on the degree of drying to be achieved,where small amounts of residual solvents and or other volatilecomponents can optionally be removed at relatively high temperature andin combination with sintering, which is preferably to be carried out.

Preferably, the drying step is followed by an annealing step whichpreferably is carried out at an elevated temperature in the range from120 to 250° C., more preferably from 140 to 240° C. and most preferablyfrom 150 to 230° C. as mentioned above with regard to the annealing ofthe different layers. Preferably, the annealing time is in the range of1 to 60 minutes, preferably in the range of 10 to 30 minutes. The dryingand the annealing step can be combined and performed as a single step.

In a preferred embodiment of the present invention, an EL organicelement of an electronic device having at least two different pixeltypes including a first pixel type (pixel A) and a second pixel type(pixel B) is manufactured wherein at least one layer of both pixel typesis deposited by applying an ink at the same time and the ink formanufacturing a layer for the pixel A and the ink for manufacturing alayer for the pixel B which are deposited at the same time can be sameor different.

A pixel type is a part of the the electronic device having the samefeatures, e. g. the same colour. Preferably, the at least two the pixeltypes (A) and (B) differ in their colour. In a specific embodiment, theelectronic device preferably has three different pixel types. Thesethree pixel types preferably differ in their colour.

The expression “applying an ink at the same time” means that thedifferent inks are provided to the substrate or the layer on which theinks are applied within one step. Preferably, the ink is appliedparallel, e.g. by using ink jet technique with a printing head havingtwo or more nozzles. Especially, no drying is performed between twodifferent inks are applied, if the inks are applied at the same time.

In a special embodiment, the ink for manufacturing a layer for the pixelA and the ink for manufacturing a layer for the pixel B which aredeposited at the same time are preferably different. Preferably, thepixels comprise different layers as mentioned above and below. Some ofthe layers of the different pixel may be obtained by using the same ink,e.g. in order to achieve a hole injection layer (HIL).

It should be noted that preferably, a pre-structured substrate is usedin order to achieve an electronic device. The pre-structured substratehas a specific pixel structure depending on the needs and demands of thedevice. Therefore, the different pixels may have a different area andthe different layers of each pixel may have different thicknesses. E.g.the thickness of the red pixel HTL may be different to the blue pixelHTL and the area of the blue pixel may be greater than the area of thegreen pixel.

In the embodiment as mentioned above, the ink for manufacturing a layerfor the pixel A and the ink for manufacturing a layer for the pixel Bwhich are deposited at the same time are preferably different and thedifference in the inks is preferably based on a functional materialcomprised in the ink. Preferably, the difference in the inks beingpreferably based on a functional material concerns the type of thefunctional material, e.g. in the color of the EML is due to thefunctional material of the ink used to achieve a specific colour.

In a further embodiment of the present invention, the ink formanufacturing a layer for the pixel A and the ink for manufacturing alayer for the pixel B which are deposited at the same time are differentand the difference in the inks is preferably based on a concentration ofa functional material comprised in the ink.

Furthermore, the ink for manufacturing a layer for the pixel A and theink for manufacturing a layer for the pixel B preferably comprises anidentical solvent. Preferably, the inks for manufacturing a layer forthe pixel A and the ink for manufacturing a layer for the pixel Bcomprising an identical solvent are deposited at the same time and aredifferent. In a specific embodiment, the ink for manufacturing a layerfor the pixel A and the ink for manufacturing a layer for the pixel Bpreferably comprises at least 50% by weight, preferably at least 80% byweight of one or more identical solvents.

In a specific embodiment of the present invention, the ink formanufacturing a layer for the pixel A and the ink for manufacturing alayer for the pixel B which are deposited at the same time can be sameor different and the difference in the inks is preferably based on asolvent comprised in the inks.

Preferably, the ink for manufacturing a layer for the pixel A and theink for manufacturing a layer for the pixel B which are deposited at thesame time are different and the difference in the inks is based on asolvent, wherein the ink for manufacturing a layer of pixel A comprisesa solvent A and the ink for manufacturing a layer of pixel B comprises asolvent B. In a specific embodiment, the ink for obtaining a layer ofpixel A preferably comprises at least 50% by weight of solvent A.Preferably, the ink for obtaining a layer of pixel B comprises at least50% by weight of solvent B. The solvent A is different to the solvent B.

In a preferred further embodiment, the difference between the boilingpoint of solvent A and the boiling point of solvent B is preferablybelow 80° C., more preferably below 60° C. and most preferably below 40°C.

It may furthermore be provided that the process is repeated a number oftimes, with formation of different or identical functional layers.Crosslinking of the functional layer formed can take place here in orderto prevent dissolution thereof, as disclosed, for example, in EP 0 637899 A1.

In a preferred embodiment, the ink deposited is preferably deposited ona substrate or a layer and the contact angle between the ink and thetarget surface is at most 45°, preferably at most 20° and morepreferably at most 10° determined by measuring the point of intersectionbetween the drop contour and the baseline of the surface at theapplication temperature, preferably at 25° C.

The present invention also relates to an electronic device obtainable bya method according to the present invention.

In FIG. 1, a schematic view of a preferred device is shown having a bluecommon layer (BCL) structure. The device comprises a substrate, acathode which may be provided with an electron injection layer (EIL) andfurthermore, the device comprises three pixel types, one pixel typehaving a blue colour, one pixel type having a green colour and one pixeltype having a red colour. All the pixel types have a HIL, a HTL, anemission layer and an electron transport layer (ETL). As shown, all thepixel types are separated and have specific layers such as ahole-injection layer for red (R-HIL), hole-injection layer for green(G-HIL), hole-injection layer for blue (B-HIL), hole transport layer forred (R-HTL), hole transport layer for green (G-HTL), hole transportlayer for blue (B-HTL), green emissive layer (G-EML), and red emissivelayer (R-EML). The emission layer for the blue pixel is formed as a bluecommon layer (BCL) which is also provided to the green and red pixel.Preferably, the common blue layer is deposited by a vacuum depositionprocess as discussed above and below.

The present invention furthermore relates to an electronic device havingat least one functional layer comprising at least one organic functionalmaterial which is obtainable by the above-mentioned process for theproduction of an electronic device.

An electronic device is taken to mean a device comprising two electrodesand at least one functional layer in between, where this functionallayer comprises at least one organic or organometallic compound.

The organic electronic device is preferably an organicelectroluminescent device (OLED), a polymeric electroluminescent device(PLED), an organic light-emitting transistor (O-LET), a light-emittingelectrochemical cell (LEC) or an organic laser diode (O-laser).

Active components are generally the organic or inorganic materials whichare introduced between the anode and the cathode, where these activecomponents effect, maintain and/or improve the properties of theelectronic device, for example its performance and/or its lifetime, forexample charge-injection, charge-transport or charge-blocking materials,but in particular emission materials and matrix materials. The organicfunctional material which can be employed for the production offunctional layers of electronic devices accordingly preferably comprisesan active component of the electronic device.

Organic electroluminescent devices (OLEDs) are a preferred embodiment ofthe present invention. The OLED comprises a cathode, an anode and atleast one emitting layer.

It is furthermore preferred to employ a mixture of two or more tripletemitters together with a matrix. The triplet emitter having theshorter-wave emission spectrum serves as co-matrix here for the tripletemitter having the longer-wave emission spectrum.

The proportion of the matrix material in the emitting layer in this caseis preferably between 50 and 99.9% by volume, more preferably between 80and 99.5% by volume and most preferably between 92 and 99.5% by volumefor fluorescent emitting layers and between 70 and 97% by volume forphosphorescent emitting layers.

Correspondingly, the proportion of the dopant is preferably between 0.1and 50% by volume, more preferably between 0.5 and 20% by volume andmost preferably between 0.5 and 8% by volume for fluorescent emittinglayers and between 3 and 15% by volume for phosphorescent emittinglayers.

An emitting layer of an organic electroluminescent device may alsoencompass systems which comprise a plurality of matrix materials(mixed-matrix systems) and/or a plurality of dopants. In this case too,the dopants are generally the materials whose proportion in the systemis the smaller and the matrix materials are the materials whoseproportion in the system is the greater. In individual cases, however,the proportion of an individual matrix material in the system may besmaller than the proportion of an individual dopant.

The mixed-matrix systems preferably comprise two or three differentmatrix materials, particularly preferably two different matrixmaterials. One of the two materials here is preferably a material havinghole-transporting properties or a wide-band-gap material and the othermaterial is a material having electron-transporting properties. However,the desired electron-transporting and hole-transporting properties ofthe mixed-matrix components may also be combined principally orcompletely in a single mixed-matrix component, where the furthermixed-matrix component(s) fulfil(s) other functions. The two differentmatrix materials may be present here in a ratio of 1:50 to 1:1,preferably 1:20 to 1:1, more preferably 1:10 to 1:1 and most preferably1:4 to 1:1. Mixed-matrix systems are preferably employed inphosphorescent organic electroluminescent devices. Further details onmixed-matrix systems can be found, for example, in WO 2010/108579.

Apart from these layers, an organic electroluminescent device may alsocomprise further layers, for example in each case one or morehole-injection layers, hole-transport layers, hole-blocking layers,electron-transport layers, electron-injection layers, exciton-blockinglayers, electron-blocking layers, charge-generation layers (IDMC 2003,Taiwan; Session 21 OLED (5), T. Matsumoto, T. Nakada, J. Endo, K. Mori,N. Kawamura, A. Yokoi, J. Kido, Multiphoton Organic EL Device HavingCharge Generation Layer) and/or organic or inorganic p/n junctions. Itis possible here for one or more hole-transport layers to be p-doped,for example with metal oxides, such as MoO₃ or WO₃, or with(per)fluorinated electron-deficient aromatic compounds, and/or for oneor more electron-transport layers to be n-doped. It is likewise possiblefor interlayers, which have, for example, an exciton-blocking functionand/or control the charge balance in the electroluminescent device, tobe introduced between two emitting layers. However, it should be pointedout that each of these layers does not necessarily has to be present.

The thickness of the layers, for example the hole-transport and/orhole-injection layer, can preferably be in the range from 1 to 500 nm,more preferably in the range from 2 to 200 nm.

In a further embodiment of the present invention, the device comprises aplurality of layers. The ink according to the present invention canpreferably be employed here for the production of a hole-transport,hole-injection, electron-transport, electron-injection and/or emissionlayer.

The present invention accordingly also relates to an electronic devicewhich comprises at least three layers, but in a preferred embodiment allsaid layers, from hole-injection, hole-transport, emission,electron-transport, electron-injection, charge-blocking and/orcharge-generation layer and in which at least one layer has beenobtained by means of an ink to be employed in accordance with theinvention.

The device may furthermore comprise layers built up from furtherlow-molecular-weight compounds or polymers which have not been appliedby the use of inks. These can also be produced by evaporation oflow-molecular-weight compounds in a high vacuum.

It may additionally be preferred to use the compounds to be employed notas the pure substance, but instead as a mixture (blend) together withfurther polymeric, oligomeric, dendritic or low-molecular-weightsubstances of any desired type. These may, for example, improve theelectronic or emission properties of the layer.

In a preferred embodiment of the present invention, the organicelectroluminescent device here may comprise one or more emitting layers.If a plurality of emission layers are present, these preferably have aplurality of emission maxima between 380 nm and 750 nm, resultingoverall in white emission, i.e. various emitting compounds which areable to fluoresce or phosphoresce are used in the emitting layers. Veryparticular preference is given to three-layer systems, where the threelayers exhibit blue, green and orange or red emission (for the basicstructure see, for example, WO 2005/011013). White-emitting devices aresuitable, for example, as backlighting of LCD displays or for generallighting applications.

It is also possible for a plurality of OLEDs to be arranged one abovethe other, enabling a further increase in efficiency with respect to thelight yield to be achieved.

In order to improve the out-coupling of light, the final organic layeron the light-exit side in OLEDs can, for example, also be in the form ofa nanofoam, resulting in a reduction in the proportion of totalreflection.

In a specific embodiment of the present invention, a common layer isdeposited by vacuum deposition technique. Common layer means a layerwhich is applied for all the different pixel types. Preferably, thecommon layer being deposited by vacuum deposition technique comprises alight emitting material.

Preference is furthermore given to an OLED in which one or more layersare applied by means of a sublimation process, in which the materialsare applied by vapour deposition in vacuum sublimation units at apressure below 10⁻⁵ mbar, preferably below 10⁻⁶ mbar, more preferablybelow 10⁻⁷ mbar.

It may furthermore be provided that one or more layers of an electronicdevice according to the present invention are applied by means of theOVPD (organic vapour phase deposition) process or with the aid ofcarrier-gas sublimation, in which the materials are applied at apressure between 10⁻⁵ mbar and 1 bar.

It may furthermore be provided that one or more layers of an electronicdevice according to the present invention are produced from solution,such as, for example, by spin coating, or by means of any desiredprinting process, such as, for example, screen printing, flexographicprinting or offset printing, but particularly preferably LITI (lightinduced thermal imaging, thermal transfer printing) or inkjet printing.

An orthogonal solvent can preferably be used here, which, althoughdissolving the functional material of a layer to be applied, does notdissolve the layer to which the functional material is applied.

The device usually comprises a cathode and an anode (electrodes). Theelectrodes (cathode, anode) are selected for the purposes of the presentinvention in such a way that their band energies correspond as closelyas possible to those of the adjacent, organic layers in order to ensurehighly efficient electron or hole injection.

The cathode preferably comprises metal complexes, metals having a lowwork function, metal alloys or multilayered structures comprisingvarious metals, such as, for example, alkaline-earth metals, alkalimetals, main-group metals or lanthanoids (for example Ca, Ba, Mg, Al,In, Mg, Yb, Sm, etc.). In the case of multilayered structures, furthermetals which have a relatively high work function, such as, for example,Ag, can also be used in addition to the said metals, in which casecombinations of the metals, such as, for example, Ca/Ag or Ba/Ag, aregenerally used. It may also be preferred to introduce a thin interlayerof a material having a high dielectric constant between a metalliccathode and the organic semiconductor. Suitable for this purpose are,for example, alkali-metal or alkaline-earth metal fluorides, but alsothe corresponding oxides (for example LiF, Li₂O, BaF₂, MgO, NaF, etc.).The layer thickness of this layer is preferably between 0.1 and 10 nm,more preferably between 0.2 and 8 nm, and most preferably between 0.5and 5 nm.

The anode preferably comprises materials having a high work function.The anode preferably has a potential greater than 4.5 eV vs. vacuum.Suitable for this purpose are on the one hand metals having a high redoxpotential, such as, for example, Ag, Pt or Au. On the other hand,metal/metal oxide electrodes (for example Al/Ni/NiO_(x), Al/PtO_(x)) mayalso be preferred. For some applications, at least one of the electrodesmust be transparent in order to facilitate either irradiation of theorganic material (O-SCs) or the coupling-out of light (OLEDs/PLEDs,O-lasers). A preferred structure uses a transparent anode. Preferredanode materials here are conductive, mixed metal oxides. Particularpreference is given to indium tin oxide (ITO) or indium zinc oxide(IZO). Preference is furthermore given to conductive, doped organicmaterials, in particular conductive, doped polymers, such as, forexample, poly(ethylenedioxythiophene) (PEDOT) and polyaniline (PANI) orderivatives of these polymers. It is furthermore preferred for a p-dopedhole-transport material to be applied as hole-injection layer to theanode, where suitable p-dopants are metal oxides, for example MoO₃ orWO₃, or (per)fluorinated electron-deficient aromatic compounds. Furthersuitable p-dopants are HAT-CN (hexacyanohexaazatriphenylene) or thecompound NPD9 from Novaled. A layer of this type simplifies holeinjection in materials having a low HOMO energy, i.e. an HOMO energywith a large negative value.

In general, all materials which are used for the layers in accordancewith the prior art can be used in the further layers of the electronicdevice.

The electronic device is correspondingly structured in a manner knownper se, depending on the application, provided with contacts and finallyhermetically sealed, since the lifetime of such devices is drasticallyshortened in the presence of water and/or air.

The inks useful for the present invention and the electronic devices, inparticular organic electroluminescent devices, obtainable therefrom aredistinguished over the prior art by one or more of the followingsurprising advantages:

-   -   1. The electronic devices obtainable using the methods according        to the present invention exhibit very high stability and a very        long lifetime compared with electronic devices obtained using        conventional methods.    -   2. The electronic devices obtainable using the methods according        to the present invention exhibit a high efficiency, especially a        high luminance efficiency and a high external quantum        efficiency.    -   3. The inks useful for the present invention can be processed        using conventional methods, so that cost advantages can also be        achieved thereby.    -   4. The organic functional materials employed in the methods        according to the present invention are not subject to any        particular restrictions, enabling the process of the present        invention to be employed comprehensively.    -   5. The layers obtainable using the methods of the present        invention exhibit excellent quality, in particular with respect        to the uniformity of the layer.    -   6. The inks useful for the present invention can be produced in        a very rapid and easy manner using conventional methods, so that        cost advantages can also be achieved thereby.

These above-mentioned advantages are not accompanied by an impairment ofthe other electronic properties.

It should be pointed out that variations of the embodiments described inthe present invention fall within the scope of this invention. Eachfeature disclosed in the present invention can, unless this isexplicitly excluded, be replaced by alternative features which serve thesame, an equivalent or a similar purpose. Thus, each feature disclosedin the present invention is, unless stated otherwise, to be regarded asan example of a generic series or as an equivalent or similar feature.

All features of the present invention can be combined with one anotherin any way, unless certain features and/or steps are mutually exclusive.This applies, in particular, to preferred features of the presentinvention. Equally, features of non-essential combinations can be usedseparately (and not in combination).

It should furthermore be pointed out that many of the features, and inparticular those of the preferred embodiments of the present invention,are themselves inventive and are not to be regarded merely as part ofthe embodiments of the present invention. For these features,independent protection can be sought in addition or as an alternative toeach invention presently claimed.

The teaching on technical action disclosed in the present invention canbe abstracted and combined with other examples.

The invention is explained in greater detail below with reference toworking examples, but without being restricted thereby.

WORKING EXAMPLES Example 1

A device having only a blue pixel is produced having a blue emissionlayer which is obtained by a vacuum deposition process. The thickness ofthe cathode is 100 nm, the thickness of the ETL is 20 nm, the thicknessof the blue common layer is 25 nm, the thickness of the blue HTL (B-HTL)is 40 nm, the thickness of the HIL is 30 nm, the thickness of the ITOanode is 50 nm.

The used ink set 1 has the following features:

Concentration Viscosity Surface tension Layer Ink code (g/L) (cp) (mN/m)HIL MBL3- 16 3.6 33 6300 B-HTL MHL3- 8.5 3.3 33 2973 The inks used, arecommercially available products of Merck KGaA

The following devices are obtained by the following annealingtemperatures

LT95 at Anneal Temperature EQE (%) @ 1,000 (° C.) ∧max @ 10000 cd/m²Device T1 T2 T3 (nm) cd/m² (hrs) remark A 180 210 200 na na na Noemission B 180 230 150 447 7.23 69 Spots in the devices C 180 210 150447 7.45 216 D 200 210 150 447 7.54 286 E 200 200 150 447 7.09 425 F 200190 150 447 6.89 495 G 200 180 150 447 6.42 592 Very good lifetime

These data clearly show that Device A does not provide an acceptableperformance, while Device B has a low performance. The other deviceshave a good or excellent performance.

The measurements of Λmax (nm), EQE (%)@1000 cd/m² and LT95@1,000 cd/m²(hrs) are achieved with the following methods:

The devices are driven with constant voltage provided by a Keithley 230voltage source. The voltage over the device as well as the currentthrough the device are measured with two Keithley 199 DMM multimeters.The brightness of the device is detected with a SPL-025Y brightnesssensor, a combination of a photodiode with a photonic filter. The photocurrent is measured with a Keithley 617 electrometer. For the spectra,the brightness sensor is replaced by a glass fiber which is connected tothe spectrometer input. The device lifetime is measured under a givencurrent with an initial luminance. The luminance is then measured overtime by a calibrated photodiode.

Example 2

A device as mentioned in FIG. 1 is prepared having the following pixelfeatures:

Red Green Blue Cathode (AI) 100 nm  100 nm  100 nm  ETL 20 nm 20 nm 20nm BCL 25 nm 25 nm 25 nm EML 60 nm 60 nm — HTL 20 nm 20 nm 40 nm HIL 60nm 30 nm 30 nm Anode (ITO) 50 nm 50 nm 50 nm

The used ink set 1 has the following features:

Ink set 1 Concentration Viscosity Surface tension Layer Ink code (g/L)(cp) (mN/m) HIL MBL3- 16 3.6 33 6300 RG-HTL MHL3- 5.5 6 38 1484 B-HTLMHL3- 8.5 3.3 33 2973 G-EML MRE3- 19.5 4.7 38 2502 R-EML MRE3- 15.5 4.638 4067 The inks used, are commercially available products of Merck KGaA

The device is prepared as mentioned as follows:

Glass substrates covered with pre-structured ITO and bank material werecleaned using ultrasonication in isopropanol followed by de-ionizedwater, then dried using an air-gun and a subsequent annealing on ahot-plate at 230° C. for 2 hours.

HIL inks were printed and vacuum dried. The HIL was then annealed at210° C. for 30 minutes in air.

On top of the HIL for green and red devices, green and redhole-transport layer (G-HTL and R-HTL) was inkjet-printed, dried invacuum and annealed at 210° C. for 30 minutes in nitrogen atmosphere.

For green and red devices, the green and red emissive layer (G-EML andR-EML) were also inkjet-printed, vacuum dried and annealed at 140° C.for 10 minutes in nitrogen atmosphere. For blue device, the bluehole-transport layer (B-HTL) was inkjet-printed, vacuum dried andannealed at 140° C. for 10 minutes in nitrogen atmosphere.

All inkjet printing processes were performed under yellow light andunder ambient conditions.

The devices were then transferred into a vacuum deposition chamber wherethe deposition of a common blue emissive layer (BCL), anelectron-transport layer (ETL), electron injection layer (EIL) and acathode (Al) was done using thermal evaporation (see FIG. 1).

In the ETL, ETM-1 was used as a hole-blocking material. The material hasthe following structure:

In the electron transport layer (ETL) a 50:50 mixture of ETM-1 and LiQwas used. LiQ is lithium 8-hydroxyquinolinate.

Finally, the Al electrode is vapor-deposited. The devices were thenencapsulated in a glove box and physical characterization was performedin ambient air. FIG. 1 shows the device structure.

The following performance is measured using the methods mentioned above.

Device Performance:

LT80 at EQE (%) @ 1,000 Anneal Temperature (° C.) ∧max @ 1000 cd/m²Device T1 T2 T3 (nm) cd/m² (hrs) R 210 210 140 621 16.8 4,700 G 210 210140 520 17 20,500 B 210 210 140 448 8 740

Example 3

Example 2 is essentially repeated but the following ink set is used:

Ink set 2 Concentration Viscosity Surface tension Layer Ink code (g/L)(cp) (mN/m) HIL MBL3- 16 3.6 33 1156 RG-HTL MHL3- 7 4.4 33 6989 B-HTLMHL3- 11 3.4 33 1927 G-EML MGE3- 20 4.7 38 9186 R-EML MRE3- 20 4.7 383846 The inks used, are commercially available products of Merck KGaA

The following performance is measured using the methods mentioned above.

Device Performance:

LT80 at EQE (%) @ 1,000 Anneal Temperature (° C.) ∧max @ 1000 cd/m²Device T1 T2 T3 (nm) cd/m² (hrs) R 225 225 150 621 16.5 20,000 G 225 225150 520 17 40,000 B 225 225 180 448 8.2 1,000

The person skilled in the art will be able to use the descriptions toproduce further inks and electronic devices according to the presentinvention without the need to employ inventive skill and thus can carryout the invention throughout the claimed range.

1.-18. (canceled)
 19. A method for forming an organic EL element havingat least one pixel type comprising at least three different layersincluding a hole injection layer (HIL), a hole transport layer (HTL) andan emission layer (EML), wherein the HIL, the HTL and the EML of atleast one pixel type are obtained by depositing inks wherein the layersare annealed after said depositing steps in a first, second and thirdannealing step and the difference of the annealing temperature of thefirst and of the second annealing step is below 35° C., and theannealing temperature of the third annealing step is no more than 5° C.above the annealing temperature of the first and/or the second annealingstep, preferably the annealing temperature of the third annealing stepis equal to or below the annealing temperature of the first and thesecond annealing step, wherein the first annealing step is performedbefore the second annealing step and the second annealing step isperformed before the third annealing step.
 20. The method for forming anorganic EL element according to claim 19, wherein the difference of theannealing temperature of the first and of the second annealing step isbelow 25° C. and the annealing temperature of the third annealing stepis no more than 5° C. above the annealing temperature of the firstand/or the second annealing step, preferably the annealing temperatureof the third annealing step is equal to or below the annealingtemperature of the first and the second annealing step, wherein thefirst annealing step is performed before the second annealing step andthe second annealing step is performed before the third annealing step.21. The method for forming an organic EL element according to claim 19,wherein an organic EL element having at least two different pixel typesincluding a first pixel type and a second pixel type is manufactured andthe HIL and the HTL of both pixel types and the EML of at least onepixel type are obtained by depositing an ink and at least one layer ofboth pixel types is deposited by applying an ink at the same time,preferably an organic EL element having at least three different pixeltypes is manufactured and the HIL and the HTL of all pixel types and theEML of at least one pixel type are obtained by depositing an ink and atleast one layer of all pixel types is deposited by applying an ink atthe same tame.
 22. The method for forming an organic EL elementaccording to claim 20, wherein all the pixel types include a HIL and theink for obtaining a HIL comprises an organic solvent, for obtaining aHIL comprises at least 50% by weight of one or more organic solvents.23. The method for forming an organic EL element according to claim 19,wherein all the pixel types include a HIL and the HIL of all pixel typesis manufactured by depositing an ink, drying and annealing at the sametime wherein the annealing step is performed at an annealing temperatureT1.
 24. The method for forming an organic EL element according to claim20, wherein the EL element has three different pixel types including afirst pixel type, a second pixel type and a third pixel type and the HTLof the second pixel type and the third pixel type are manufactured bydepositing an ink, drying and annealing at the same time wherein theannealing step is performed at an annealing temperature T2.
 25. Themethod for forming an organic EL element according to claim 19,characterized in that the HTL of the first pixel type and the EML of thesecond pixel type are manufactured by depositing an ink, drying andannealing at the same time wherein the annealing step is performed at anannealing temperature T3.
 26. The method for forming an organic ELelement according to claim 19, wherein the annealing temperature of thefirst depositing step is at least 180° C.
 27. The method for forming anorganic EL element according to claim 19, wherein the annealingtemperature of the second depositing step is at least 180° C.
 28. Themethod for forming an organic EL element according to claim 19, whereinthe annealing temperature of the third depositing step is at least 120°C.
 29. The method for forming an organic EL element according to claim19, wherein the annealing temperature of the first depositing step is atmost 250° C.
 30. The method for forming an organic EL element accordingto claim 19, wherein the annealing temperature of the second depositingstep is at most 250° C.
 31. The method for forming an organic EL elementaccording to claim 19, wherein the annealing temperature of the thirddepositing step is at most 200° C.
 32. The method for forming an organicEL element according to claim 19, wherein at least one layer iscrosslinked during the annealing in the depositing step.
 33. The methodfor foil ling an organic EL element according to claim 19, wherein in afirst step a HIL is formed, in a second step a HTL is formed and in athird step a EML is formed wherein the HIL is formed before the HTL andthe HTL is formed before the EML.
 34. The method for forming an organicEL element according to claim 19, wherein the inks are dried before theannealing step is performed and the drying step is performed underreduced pressure.
 35. The method for forming an organic EL elementaccording to claim 19, wherein at least one layer of being obtained bydepositing an ink is inkjet-printed.
 36. The method for forming anorganic EL element according to claim 19, wherein a common layer isdeposited by vacuum deposition technique.
 37. An electronic device,obtainable by the method according to claim 19.